I’ve been trying to think of a single word counterpart to the word insidious.

Oxford Dictionaries:
insidious (adjective), Proceeding in a gradual, subtle way, but with very harmful effects.

The meaning I require (to describe the action of yeast say within dough or a must, and by metaphorical extension, small acts of kindness in society) is

Proceeding in a gradual, subtle way, with beneficial effects that eventually make a great difference.

There are related words with no implications of good or evil effect: Thesaurus.com gives synonyms for pervasive including permeating and pervading.

Is there though a single word (not a phrase, proverb … please) with the required meaning?

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    Well, I can only come up with these, which normally have a positive implication but do possibly lack the steadiness and instead illustrate a development..: thriving / evolving. I guess this is not what you are after? Jan 24, 2015 at 16:27
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    Nutrient as an adjective has that connotation. from MW, "a breakfast drink enriched with nutrient proteins and vitamins."
    – Phil Sweet
    Aug 30, 2016 at 13:27
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    Closing to update citations and improve markdown.
    – MetaEd
    Dec 21, 2017 at 15:56
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    See also another attempt to do the same: reddit.com/r/words/comments/1lk0fn/opposite_of_insidious
    – MetaEd
    Dec 21, 2017 at 16:38
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    Can I clarify something. Insidious as far as I can see describes something which is injurious to something else. So "blossoming" and "burgeoning" don't strictly seem to match, as when something blossoms it's beneficial to itself but doesn't affect other things. Along these lines I thought of "thriving", but something thrives of itself, it doesn't seem to have the agency that "insidious" haves with regard to corrupting to other things.
    – Zebrafish
    Mar 26, 2018 at 6:30

10 Answers 10


Well, it's kind of simplistic, but it can't be construed as negative... You could use "blossoming".

If you're talking about a societal trend or social movement, I'm afraid the most recognized term is a phrase: grass-roots. (It usually has positive connotations.) (US)

  • +1 And the plant-like connotation seems to fit with yeast.
    – bib
    Jan 24, 2015 at 16:08
  • Nice idea. Nice picture. Thank you. This can be used when the 'subtle, unseen beneficial processes' isn't a requirement. Jan 24, 2015 at 16:33

The term burgeoning can mean

To begin to grow or blossom. American Heritage

However, it often has a connotation of rapid or increasing growth.

  • Thank you. This can also be used when the 'subtle, unseen beneficial processes' isn't a requirement. Jan 24, 2015 at 16:33

Perhaps "nurturing" would be suitable.


I would suggest the word leavening.

Practically, leaven is any substance that, added to dough, causes it to rise and increase in size, ready for baking.

But it has, also, a metaphorical meaning :

a pervasive influence that modifies something or transforms it for the better. "they acted as an intellectual leaven to the warriors who dominated the city"


  • Thanks; certainly worth an upvote. I'm so used to the negative sense (ICor 5:8, KJV '... not with old leaven, neither with the leaven of malice and wickedness ...') that I've overlooked the more common usage in non-religious registers. However, 'insidious' has no positive nuances, and I'm hoping for a counterpart with no negative ones. Dec 22, 2017 at 10:34

Accumulative (adj) gradually increasing

Proceeding in a such a way to make accumulative progress and make a great difference

The verb germinate, which by definition is always positive, is normally reserved to biology but it can be employed in a figurative and metaphorical sense too.

Laying/Creating the perfect conditions for [it] to germinate and make a great difference

Cambridge Dictionary defines it as

germinate verb (SEED)

  1. specialized biology to (cause a seed to) start growing:

germinate verb (IDEA)

  1. to start developing: I felt an idea germinating in my head/mind.
  • Unlike the situation with 'leavening', there seem to be no denotations in dictionaries which mention 'transforms it for the better' with 'accumulative'. Debts often accumulate. // Weeds germinate, and ODO has 'germinate ... verb ... no object ... 1.2 Come into existence and develop. "the idea germinated and slowly grew into an obsession" ’. // 'Leavening' seems the best suggestion, though even this has negative connotations as well as the positive denotation given by ODO. Dec 22, 2017 at 21:04
  • @EdwinAshworth "germinate weeds", well I've never heard that one before, but if you say so. However, nearly any word can be portrayed in a positive or negative light. For example, you can be ‘insidiously good at something‘, which adds a tinge of praise and admiration.
    – Mari-Lou A
    Dec 22, 2017 at 21:20
  • Less than 1000 Google hits for 'insidiously good', and the ones I've bothered to check all tongue in cheek. // Where does 'germinate weeds' appear? I said that weeds, like all other plants, germinate. Not a positive in my gardening experience. Dec 22, 2017 at 21:26
  • @Edwin Ashworth how many hits for "germinate weed" = marijuana :) Now, germinate is mostly, practically always, positive, isn't it? P.S. I like "leavening" too. Choose that answer.
    – Mari-Lou A
    Dec 22, 2017 at 21:28
  • I'd say it's largely neutral. There are plenty of negative examples, on the internet, thousands for germinated + Nazi, say. Dec 22, 2017 at 21:36

Osmosis can be used figuratively for this sense:

a gradual process in which information and ideas influence you without you realizing it

I picked up the language mainly by osmosis.


  • Yes, but it's at best neutral. One can pick up racism by osmosis. Jan 24, 2015 at 17:37
  • Yes but maybe this is the closest it gets as it can connote a positive sense also.
    – ermanen
    Jan 24, 2015 at 17:50
  • It doesn't to me; osmosis is fundamentally a physical process undergone by fluids. Nothing good or evil there. Certainly, it can be used metaphorically with processes that are good (learning a new language) or bad (learning bad language), but that doesn't mean it connotes good or evil. With insidious, the evil aspect is even part of the definition (denotation). Jan 24, 2015 at 20:31

Consider "edifying"

Adj. 1. edifying - enlightening or uplifting so as to encourage intellectual or moral improvement; "the paintings in the church served an edifying purpose even for those who could not read"

  • Perhaps there's a nod here to the gradualness of the process, but it's ballpark rather than a near miss. Aug 30, 2016 at 21:58

This may come off a bit obvious, for which I apologize.

Serendipity: Luck that takes the form of finding valuable or pleasant things that are not looked for.

The effects are good, but they appear suddenly, and develop stealthily without one knowing.


  • Develop stealthily? I don't see that 'serendipity' covers this. Aug 30, 2016 at 21:55
  • Insomuch as the good fortune is not sought out.
    – user191160
    Aug 30, 2016 at 21:58
  • But serendipitous events are punctive (appear suddenly), as you say. This is the counterpart of calamity, not insidiousness. Aug 30, 2016 at 22:15


From the verb to enhance:

Intensify, increase, or further improve the quality, value, or extent of.

I particularly like this because the PIE root of insidious is *sed- meaning "to sit". While enhance has a Latin root in altare, "to raise up", which is a nice parallel; it has a further PIE root *al- meaning "to grow, nourish" which nicely matches the yeast example.

  • Sorry; this in no way even connotes the gradualness / subtleness I required. Dec 21, 2017 at 18:25

I'm not exactly sure what you require, especially since I was confused by the yeast bit. But I'll try:

Having the ability to restore health, strength, or well-being. ‘the restorative power of long walks’ Oxford Living Dictionaries

I know you're looking for a word that connotes slow-acting. This may fit depending on what the restorative is. If you're dehydrated, drinking water will ameliorate the problem very quickly. However with most physical treatments I believe they are generally slow-acting.

1. To restore to good health or useful life, as through therapy and education
American Heritage Dictionary

This word necessarily in my opinion implies a slow-acting process. However a problem I see with it is that it implies a fault from which to be rehabilitated.

I also thought of convalescent, but in the definitions I saw it is very specific to recovering patients.

You can tell I'm thinking in physical health terms here.

  • Yes; thanks. But 'insidious' has a very broad distribution, not just in the physiological domain but with regard to dry rot, certain weeds, and especially harmful but sub-surface trends in society. It is also often used to describe a harmful deterioration from a neutral state. Mar 26, 2018 at 7:51

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