Some words in English pronunciation can lose a syllable when they are said quickly. Listen to the word SPECIALIST said twice:
The schwa sound /ə/ is optional, so you might say SPE-CIA-LIST, or you might say SPEC-LIST. The word can be two or three syllables in length.
When can silent syllables occur?
Silent syllables are common in words of three or more syllables where there is a weak vowel sound followed by one of /l/, /r/ or /n/. Both pronunciations of these words are correct, though in connected speech, the silent syllable is more likely in most cases.
Some common examples are:
The weak vowel sound that will be silent if a silent syllable appears, is in brackets in the IPA transcriptions: (ə).