I've noticed that in English, "some words" (I don't know if it could be used on all words) could be prefixed by the letter "a" to change the meaning, here are a few examples:

Side and Aside

Like and Alike

Live and Alive

Way and Away

Mount and Amount

Round and Around


What is the name of this "grammatical phenomenon" ?

Is there a general rule to know the meaning of a prefixed word from its base word without using the dictionary?

  • 1
    Some of these are not like the others. You are mixing apples and motorbikes here. There is no useful hypernym for that other than "things" or "stuff". – RegDwigнt Oct 5 '18 at 12:30
  • You forgot "amoral", "asymmetrical", and and a few others. – Hot Licks Oct 5 '18 at 12:52
  • See here: a- (1) prefix or inseparable particle, a relic of various Germanic and Latin elements. a- (2) word-forming element meaning "away," from Latin a "off, of, away from," the usual form of Latin ab before consonants (see ab-). a- (3) prefix meaning "not, without," from Greek a-, an- "not" (the "alpha privative"), from PIE root *ne- "not" (source also of English un-). etymonline.com/word/a- – user240918 Oct 5 '18 at 13:31
  • @RegDwigнt "You are mixing apples and motorbikes here" LoL I can't stop laughing but seriously, for example to mount means climb or move up on to (a raised surface) and amount is a sum of something (The total), so the similarity here is that when you climb you are moving up toward the tip and when calculate an amount you are basically adding up or "moving up" to the total number of something. – CryptoBird Oct 5 '18 at 13:58
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    @HotLicks pretty sure those examples are cases of privative A. I'm not sure if what OP is talking about is related to something like: "laughin' and a-runnin', hey hey, skippin' and a-jumpin'. Probably not. – Zebrafish Oct 5 '18 at 14:43

Using Online Etymology Dictionary as a source, it seems that in most examples the initial 'a' in these words are from roughly the same morphemic meaning, with the exception of "amount". I've quoted the meaning I think is relevant to your words.

a- (1) In words derived from Old English, it commonly represents Old English an "on, in, into" (see on (prep.)), as in alive, above, asleep, aback, abroad, afoot, ashore, ahead, abed, aside, etc., forming adjectives and adverbs from nouns, with the notion "in, at; engaged in." In this use it is identical to a (2).

"away or apart from a normal direction or position, out of the way," from a- (1) "on" + side (n.).

from Old English an, on (see a- (1) + like (adj.)

c. 1200, "in life, living," contraction of Old English on life "in living, not dead," from a- (1) + dative of lif "life" (see life).

"on from this (that) place;" see a- (1) + way (n.)

from phrase on round; see a- (1) + round (adj.).

The exception seems to be "amount"

a contraction of the prepositional phrase a mont, from a (from Latin ad "to;" see ad-)

Where the a- prefix seems to have been originally from Latin ad- (to/towards) which went through Old French and became a-.

Latin ad-
In Old French, reduced to a- in all cases
Latin ad-

So it seems that in most of your particular cases the a- prefix seems to have come from the first meaning listed.

However take note that I only mentioned one meaning of the Old English a- prefix, because this was the one that seemed applicable to your words.

As the Online Etymology Dictionary says, in words like anew, afresh, akin and abreast the a- has probably a meaning of:

Middle English of (prep.) "off, from,", and in

And in words like abide, arise, awake, ashamed the a- is either:

Old English intensive a-


probably implying originally "motion away from"


marking a verb as momentary, a single event.

Given that the initial and pften distinguishable a- part of the word can, or at least used to mean so many different things, it's not surprising that The Etymology Dictionary includes this note from the OED:

[I]t naturally happened that all these a- prefixes were at length confusedly lumped together in idea, and the resultant a- looked upon as vaguely intensive, rhetorical, euphonic, or even archaic, and wholly otiose. [OED]
a- prefix

As for the name of this a- prefix, I have no idea, I'm sorry. From what I read I only know it as the Old English a- prefix or particle. I doubt that a name for this would be particularly helpful from a descriptive point of view, because it just can mean so many things. Compare this with the Greek privative A below, which is very consistent in its meaning and does have a name.

As for what phenomenon this is, I can't think of anything more general than "prefixation" (adding of a prefix to a word).

One thing the a- prefix doesn't mean in your words is what the a- prefix means in "atypical", "apolitical", "atonal", "achromatic". The a- here is completely different from any of the words mentioned above. It's Greek meaning negation or absence.
Alpha privative or privative A

Also, to answer your question:

Is there a general rule to know the meaning of a prefixed word from its base word without using the dictionary?

In the case of this Old English a- prefix, definitely not. However there are other prefixes which are much more consistent. If you see a word beginning with un- or in- followed by a word separately recognisable you can have an idea it means its opposite or its negation. There are exceptions though, like the famous flammable/inflammable, or even "famous" and "infamous"; "infamous" meaning you're still famous but for a different reason.

So you can pick up general rules, but I don't know of anything bulletproof.

  • (+1) Maaaaan, I don't what to say, words can't express how I feel, you went above and beyond, thanks a million. – CryptoBird Oct 5 '18 at 22:38

There is no name for this phenomenon you have observed, and no common 'origin story'. Often the 'a-' was originally a modifier indicating a word such as on or in. These a-words will tend to be either a contraction of a longer phrase (usually a 'prepositional phrase') or a corruption of an older compound word. The original may be from any language commonly absorbed into English, for example French (amount) or Old English (away/alive) .

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