However, depending on the context, you could use:
For poetry:
* Elision: This is the most accurate term for omitting a sound or syllable to achieve a certain rhythm or meter.
* Syncope: This specifically refers to the omission of a vowel or syllable within a word.
For speech:
* Slur: This implies that syllables are not clearly pronounced, but rather run together.
* Reduction: This describes the shortening or omission of a sound or syllable, often due to casual speech patterns.
* Informal language: You might simply say "skip a syllable" or "leave out a syllable" in casual conversation.
The best term depends on the specific situation and the level of formality you require.