Can someone provide the proper academic terms and explanations for why we pronounce the roots of the following words differently:

sociopath vs. sociopathy

telepath vs. telepathy

biographic vs. biography

And along the same lines, is it related in anyway to the same change that occurs in

athlete vs. athletic

episode vs. episodic

I was explaining the concept to my daughter and realized I had no backing other than "it sounds nicer" (which certainly they do) and would like something a little more solid.

EDIT: This is not merely asking why certain words are stressed where they are, but why suffixes and variations cause the pronunciation of certain words to change almost completely. So not simply the shift from U-ni-verse to to u-ni-VERS-i-ty, but the shift from tuh-LEH-puh-THY to TEL-uh-PATH.

I've updated the title to reflect it's the change in pronunciation not simply the change in stress that I'm interested in.

  • 2
    Possible duplicate of Why is "omnipotent" stressed iambically?, where it's pointed out that It is very frequent, at least in BrE, that long Latin/Greek words are stressed on the third-last syllable. Commented Oct 21, 2015 at 16:09
  • 1
    Many suffixes shift the stress forward one syllable; -ic/-ical and -ity are examples: history/historic, hermit/hermetical, fraternize/fraternity. Most of this is simple inheritance of the Latin stress rule, using suffixes that were already attached when the word was borrowed into English. Commented Oct 21, 2015 at 17:58
  • @FumbleFingers except sociopath doesn't emphasize the third-last syllable (nor does biographic) so it's not merely following a rule.
    – Kyle Hale
    Commented Oct 21, 2015 at 18:36
  • @Kyle Hale: It's a tendency, not a "rule" (but it does apply to all OP's examples - sociopathy, telepathy, biography). Commented Oct 22, 2015 at 12:07

1 Answer 1


This is actually a pretty complicated topic.

The change in the pronunciation of the vowels can be considered a secondary effect of the change in stress. Changing the pronunciation of a vowel in an unstressed syllable is called "vowel reduction". In "telepath", the first syllable is stressed, so the vowel is pronounced as unreduced /ɛ/, whereas in "telepathy", the first syllable is unstressed, so the vowel is reduced to schwa /ə/.

In stressed syllables, single vowel letters can usually be pronounced at least two ways in English (one of the most notorious features of its spelling) but a complete account of the rules for vowel pronunciation in stressed syllables based on the context would be rather long and I don't think the examples really call for it. So the rest of this answer will just be about stress patterns.

In sociopathy, telepathy and biography, the stress is on the third-to-last or "antepenultimate" syllable. This is actually a fairly common position for stress in Latinate words, and "sociopathy" and "telepathy" belong to a particular subtype of words where this stress shift is common: compounds of Greek roots ending in -y, where the second element ends in a single consonant. I know that explanation is a bit complicated, so here are a few examples: geology, geography, astronomy and in general words ending in -logy, -graphy, -nomy, -phony, -scopy.

Anther noun ending that causes stress to fall on the antepenult syllable is -ity.

However, I don't know enough phonological theory to explain why this stress pattern is used in these words.

Athletic, episodic and biographic are examples of a rule that adjectives ending in the suffix -ic are stressed on the second-to-last syllable (with some exceptions).

Some people have tried to explain the -ic stress rule as resulting from the application of the third-to-last rule by using certain abstract analyses of the structure of words, but I haven't yet seen an explanation along these lines that seemed convincing to me. (For example, Chomsky and Halle's The Sound Pattern of English (1968) argued that "-ic" words with stress on the second-to-last syllable have an underlying form with an extra syllable "al" that has been deleted; this is not entirely unmotivated as "ic" words do often coexist with "ical" words with "al" explicitly present, and there is a spelling rule by which adjectives ending in "ic" usually correspond to adverbs ending in "ically", but nevertheless it seems rather far-fetched. This analysis is mentioned by Erik Fudge in "English Word Stress: Basic Assumptions", a paper in Essays on the Sound Pattern of English (1975), edited by Didier L. Goyvaerts and Geoffrey K. Pullum. A different explanation given by Jonathan B. Alcántara in "The Architecture of the English Lexicon" (1998) is that words like "athletic" and "episodic" actually end in a segment /ə/ that "is never allowed to surface, but will provide a final syllable" that explains the stress pattern of these words (3-114). In other words, the suffix spelled "ic" is in some way really /-icə/.)

There are other monosyllabic suffixes that behave similarly to -ic, such as the adjective suffix -id, the verb suffix -ish, and the noun suffix -ule. It has been observed that these (and also the disyllabic suffixes that commonly trigger trisyllabic shortening, like -ity, -ify, -ular, -ual, and according to Alcántara -ible, although I'm unsure if this suffix is actually a very consistent trigger of a short vowel in the preceding syllable) all start with high vowels (Alcántara A-310), but I'm not sure if this is significant in the way it might be taken to be; these endings are from Latin endings that contained short vowels (e.g. -ĭcus, -ĭdus, -ŭlus, -ĭtās, -ĭfĭcāre, -ĭbĭlis, -ŭlāris, -ŭālis) and non-high short vowels had a somewhat limited distribution in word-internal (not initial or final) open syllables in Latin due to processes of vowel reduction that turned other vowels into ĭ and ŭ in these contexts.

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