From the archives...
The following question was originally posted on the (now discontinued) LOE Forum.
What Spelling Rule tells me that I should put a silent E at the end of examine, determine, definite, chlorine, sanguine, doctrine, and famine?
There isn't a rule that tells you that you have to, but there are rules that explain why you may. In other words, you wouldn't be able to tell just from the sounds that it is there. But you can know that it might be.
1. Any vowel can say a schwa sound, /ŭ/ or /ĭ/, in an unstressed syllable or unstressed word (Spelling Rule 31.1). This means that there are many places where the "true" sound would have been a long sound if the syllable or word were stressed (as in "enough" where the first e is often pronounced /ŭ/). We use Say to Spell to remember how the word is written in these cases; for example, we would pronounce the I at the end of "definite" as long, /dē fī nīt/, in Say-to-Spell for that word, to help us remember the silent E. Keep in mind that say-to-spell doesn't change how we pronounce a word in daily speech; it's just an auditory memory tool. In most of these words we never pronounce that I as long, but in some cases we do in other forms of the word: finite, doctrinal.
In mastering the spelling of these words, it may be helpful to note that there are some common suffixes spelled this way. So if you're spelling a word that you think may use one of these suffixes, it's always worth checking for a silent E.
The adjective suffix -ine, for example, means "pertaining to, of the nature of," and the noun suffix -ine is often used to form abstract nouns or names for things that are derived from or smaller versions of something else. The i in these suffixes is pronounced with a long sound in some words, a short /ĭ/ in others, and occasionally an /ē/ sound. alpine, feline, bovine / feminine, medicine, doctrine / figurine, nectarine.
2. Chlorine is different from the others, because I says /ē/. In a small number of words I says its fourth sound /ē/ in places where we'd expect it to say its long sound: police, trampoline, tangerine, marine. This is a normal sound of I, and it is in fact a long sound (of a different phonogram), but it is not the regular long sound of I. So this spelling of the sound is unusual, but not irregular. We actually updated and expanded Spelling Rule 7 in 2018 to describe this pattern more accurately. Rule 7.2: I may say /ē/ with a silent final E, at the end of a syllable, and at the end of foreign words.