Elision /əəəəəəəəəlllllllllɪĭiɪĭiɪĭiˈˈˈˈˈˈˈˈˈʒzhzhʒzhzhʒzhzhəəəəəəəəənnnnnnnnn/  is the omission of a sound, sounds, or syllable from a word. Elision is common in speech when neighboring sounds are made at the same place of articulation or when occuring in unstressed (i.e., weak) syllables.

Syllable Elision

In spoken English, unstressed, or weak, syllables may be elided (especially in the middle of a word). Whether or not a syllable is elided can rely on a number of factors including dialect, part of speech, and placement in a sentence. 

English Word Unelided Form Elided Form
camera /kkkkkkkkkæăaæăaæăaˈˈˈˈˈˈˈˈˈmmmmmmmmmɚûrurɚûrurɚûrurəəəəəəəəə/ /kkkkkkkkkæăaæăaæăaˈˈˈˈˈˈˈˈˈmmmmmmmmmrrrrrrrrrəəəəəəəəə/
restaurant /rrrrrrrrrɛěehɛěehɛěehˈˈˈˈˈˈˈˈˈssssssssstttttttttɚûrurɚûrurɚûrurɑäahɑäahɑäahˌˌˌˌˌˌˌˌˌnnnnnnnnnttttttttt/ /rrrrrrrrrɛěehɛěehɛěehˈˈˈˈˈˈˈˈˈssssssssstttttttttrrrrrrrrrɑäahɑäahɑäahˌˌˌˌˌˌˌˌˌnnnnnnnnnttttttttt/
natural /nnnnnnnnnæăaæăaæăaˈˈˈˈˈˈˈˈˈʧchchʧchchʧchchɚûrurɚûrurɚûrurəəəəəəəəəlllllllll/ /nnnnnnnnnæăaæăaæăaˈˈˈˈˈˈˈˈˈʧchchʧchchʧchchrrrrrrrrrəəəəəəəəəlllllllll/

Some words undergo elision when pronounced in a sentence when not stressed. The word probably may be pronounced /ppppppppprrrrrrrrrɑäahɑäahɑäahˈˈˈˈˈˈˈˈˈbbbbbbbbbəəəəəəəəəbbbbbbbbbllllllllliēeeiēeeiēee/ when spoken by itself as an answer to a question:

Speaker A: "Are you going to the party?"

Speaker B: "Probably" /ppppppppprrrrrrrrrɑäahɑäahɑäahˈˈˈˈˈˈˈˈˈbbbbbbbbbəəəəəəəəəbbbbbbbbbllllllllliēeeiēeeiēee/

However, when the same word is spoken within a sentence, the pronunciaiton may change even by the same speaker.

Speaker B: "I said I'll probably /ppppppppprrrrrrrrrɑäahɑäahɑäahˈˈˈˈˈˈˈˈˈbbbbbbbbbllllllllliēeeiēeeiēee/ go after work." 

It's important for cuers to remember that the pronunication of a word can be highly variable depending on where the word occurs in a sentence and whether it is unstressed or stress (becuase it is new or important information).