A monosyllable.

27. What is a word of two syllables called?

A dissyllable.

28. What is a word of three syllables called?

A trisyllable.

29. What is a word of more than three syllables called?

A polysyllable.

30. What is the Ultimate syllable of a word?

The last syllable.

31. What is the Penultimate syllable?