Term for words that have dropped a syllable over time

Rats! And I just saw this term recently in this very forum, but I must not be searching correctly. It the term for when you have commonly understood words that over time lose a syllable (usually the prefix).

Sort-of-not-really example: if the word “inflammable” completely vanished and all we ever used was “flammable”.

Fake example with made up word: “bosmutpurdoodle” becomes “smutpurdoodle” and several generations have never heard of the original word.

It depends where the syllable is.

First syllable: aphesis, as in your example.
Middle syllable: syncope. Boatswain > bo’s’n > bosun
Final syllable: apocope.

Why not procope for number one?
I don’t know.

No, those aren’t the word I’m trying to find. It’s the term for the process by which the above terms happens. Like < term > results in aphesis, syncope, or apocope.

ETA: I’m trying to find a list of etymological terms, but I keep finding etymological dictionaries when I search.

Oh, and also, the words don’t just sound that way, like “Toronto” becoming “Tronna”, but they end up in the dictionary that way as offical words. The original word almost becoming effectively obsolete.

Oh, I misunderstood. Elision?

Limo -> Limousine?

It’s called “English place names”.

I’m pretty sure this is aphesis. Other common examples in English:

esquire -> squire
opossum -> possum

Come to think of it, I may have seen it in an answer card for the etymology and semantics game Moot.

IIRC the term is a single word. Maybe I can go through all the cards and find it. It’s a term I’d never seen before. Can you say “aphesing”? Or is “aphesis” a noun only?

FWIW, elision is the process of I am becoming I’m, etc., and every becoming ev’ry.

Squire and possum may be examples of aphesis but flammable and smutpurdoodle obtain from aphaeresis.

Meh, I could care less.

Metaplasm?

Or maybe one of the specific types of metaplasm listed here: http://rhetoric.byu.edu/figures/M/metaplasm.htm