The dictionary ascribes the same purpose to both these suffixes: to denote 'to make, or become'.

However, for some neologisms, -ize seems much more appropriate than -ify does, and vice-versa. There must be some reason for this.

Is there a rule that governs, or describes, when to use one over the other?

  • 4
    Dictionaries can only hint at the uses of suffixes; you need a grammar. Both of these are causative/inchoative suffixes, two of many in English; that's why they gave them the lame meaning 'to make, or become'. Make is used for some causative constructions: Make it so; He made me do it, and become means and originates as come to be, which is standard inchoative paraphrase. But the dictionary didn't tell you, because that's not what dictionaries do. Aug 9, 2014 at 13:42
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    Note there are a two other, though rarer, suffixes which "ify" the verb: -ate and -en, as in "flourinate" and "blacken" respectively. A quick Google Books search turned up "Word Formation in English" (Cambridge Press) which goes into this in some detail on pp 92-94, and even makes an observation about neologisms tending toward -ize, as OP does. Unfortunately, the explanation is mostly gobbledygook to me, but if someone can translate this into non-technical language, that would make a really solid answer (and earn a +1 from me). books.google.com/books?id=78KFCIHtJS4C&pg=PA93
    – Dan Bron
    Aug 9, 2014 at 13:52
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    @JohnLawler Why don't they? That seems like information people might want from a dictionary.
    – Hal
    Aug 9, 2014 at 16:34
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    @Hal: Dictionaries exist to document meanings and pronunciation of words ("lexical items"). They're lists; long lists, with sublists, but just lists. They don't -- and can't, not with lists -- describe all the ways the words can go together. That is a different kind of book, called a Grammar of English, not a Dictionary of English. This is because there is an enormous amount more to grammar than just stringing words together like beads on a string. Dictionaries can only list the beads, not describe all the possible correct and (and not the incorrect) necklaces one could make. Aug 9, 2014 at 16:42

2 Answers 2


Courtesy of @DanBron, here's what it says in Word Formation in English,
with interpolated translations:

This suffix attaches to three kinds of base word:
1. monosyllabic words
2. words stressed on the final syllable
3. words stressed on the next-to-last syllable that end in unstressed /i/

Neologisms usually do not show stress shift, but some older forms do
(húmid ~ humídify, sólid, solídify).

Translation: there are restrictions on what kind of words -ify can go on. They have to sound right. Examples of each kind of word root with -ify:

  1. pacify, crucify, gentrify (two Latin words and a neologism, all from monosyllabic roots)
  2. solemnify, malignify, machinify (likewise 2 Latin, one neo; but these are rarer)
  3. shabbify, rubify, calcify (ditto)

These restrictions have the effect that -ify is in (almost) complementary distribution with the suffix -ize.

Translation: the set of roots that can take -ify and the set of roots that can take -ize are (almost) disjoint sets. There is one intersection, which will be described next.

The only, but systematic, exception to the complementarity of -ize/-ify can be observed with (2), the base words in /i/, which take -ify with loss of the final /i/ (as in Nazify /'natsəfai/), or take -ize with no accompanying segmental changes apart from optional glide insertion (as in Nazi-ize /'natsi(y)aiz/).

Translation: you can do it either way with words stressed on the next-to-last syllable that end in unstressed /i/. But they're the only ones.

Semantically, -ify shows the same range of meanings as -ize and the two suffixes could therefore be considered phonologically conditioned allomorphs.

Translation: -ify and -ize can be considered "the same morpheme", just like a and an.

Both -ize and -ify are polysemous suffixes, which express a whole range of related concepts such as locative, provisional, causative/factitive, resultative, inchoative, performative, similative.

Translation: there are a lot of kinds of meaning (poly-semous < Gk 'many meanings') for the suffix. These types have technical names. Examples follow (I've changed a few old-fashioned terms to protect the innocent).

Locatives are paraphrased as 'put into X, as in computerize, hospitalize, tubify.
- Patinaize, fluoridize, youthify are provisional ('provide with X'),
- randomize, functionalize, humidify are causative ('make (more) X'),
- carbonize, itemize, trustify, and nazify are resultative ('make into X'),
- aerosolize and mucify are inchoative ('become X'),
- anthropologize and speechify are performative ('perform X')
- cannibalize and vampirize can be analyzed as similitive ('act like X').

The suffix -ize attaches primarily to roots ending in an unstressed syllable and the resulting derivatives show rather complex patterns of base allormorphy.

Translation: A lot of funny things happen to the roots when adding -ize. Examples follow.

For example, bases are systematically truncated (i.e, they lose the rime of the final syllable) if they are vowel-final and end in two unstressed syllables (truncated memory ~ memorize vs untruncated consonant-final hospital ~ hospitalize). Furthermore, polysyllabic derivatives in -ize are not allowed to have identical onsets in the last two syllables, if these are unstressed. In the pertinent cases truncation is used as a repair strategy, as in feminine ~ feminize and emphasis ~ emphasize.

Translation: most of the non-neologisms were formed in Latin, under Latin phonological and morphological rules, which don't apply to English. So lots of the roots are not really English words, but rather are related to English words, and it gets very complicated trying to account for all the differences between the roots and the words.

This is one example of how complex even a teensy-weensy part of English grammar can get.
And this isn't even syntax.


The suffix -fy is French fier (to make), from Latin ficare, belonging to the word familiy facere/ficere, to make. Example pacify from pax/pacis peace, pacificare to make peace. See Etymonline http://www.etymonline.com/index.php?allowed_in_frame=0&search=-fy&searchmode=none

  • I downvoted because this doesn't answer the original question.
    – herisson
    Sep 8, 2015 at 21:07

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