Why isn't "examine" pronounced like "exhamyne"? [closed]
As said, etymology can help:
Examine derives from French “examiner” while pronunciation in English has remained close to the original French term:
c. 1300, "put (someone) to question in regard to knowledge, competence, or skill, inquire into qualifications or capabilities;" mid-14c., "inspect or survey ....."from Old French examiner "
The "silent e indicates a long vowel before a preceding single consonant letter" rule of thumb is much more reliable (although not exceptionless*) for vowels in monosyllabic words, or in syllables with primary stress, than it is for vowels in non-primary-stressed syllables of words of more than one syllable.
The word "mine" is a monosyllable, like "pine", "wine", "dine".
The word "divine" has two syllables, but the last syllable takes the primary stress, so it rhymes with the monosyllables listed above.*
The word "examine" is three syllables, and the primary stressed syllable is in the middle, on the syllable containing the vowel "a". The final syllable does not have the primary stress.
When a word's spelling ends in "-ine" and the word does not have the primary stress on the last syllable, we see a variety of pronunciations.
It is possible for the word to be pronounced with a "long i" sound in the last syllable (IPA /aɪn/);
but it is also possible for the vowel to be "reduced" to a "short i" sound (IPA /ɪn/; in most American accents, this may merge with the "schwa + n" or "syllabic n" sound to become /ən/ or /n̩/, which makes "examine" rhyme with "salmon").
In a few words, we may even hear a "long e" sound (IPA /iːn/), probably due to influence from French pronunciation (e.g. "alexandrine", "guanine").*
Many words ending in non-primary-stressed "-ine" actually have variable pronunciations.
Other words where "-ine" is pronounced like in "imagine" are examine, famine, medecine, urine, masculine, feminine, Katherine/Catherine, margarine, jasmine. This is not a comprehensive list; it's just meant to show that this is not rare.
*Actually, even in stressed syllables, there are a few words where "-ine" is pronounced with a "long e" sound (IPA /iːn/) rather than a "long i" sound; for example, "marine".
The pronunciation of English words often depends on their etymology (i.e. the root language that they derive from). Spellings may also be derived from root languages, but they may also be due to clumsy attempts by early lexicographers to impose standardised spellings, and they have simply stuck through common usage. Before dictionaries were invented, spellings of words differed wildly, and writers just used spellings that they liked, or were taught when they learned to read and write.