monosyllabic

/ˌˈmɑnəsəˌlæbɪk/

Any word or sound made up of just one syllable can be described with the adjective monosyllabic.

Monosyllabic comes from the Greek prefix monos, "single," and syllabe, "syllable." You can also describe a person who tends to talk this way, in grunts or short words, as monosyllabic, like your cranky old grandpa or a newly verbal toddler.

Definitions of monosyllabic

1. adjective

   having or consisting of only one vowel or vowel-like sound, with or without consonants surrounding it
   synonyms:

   syllabic

   consisting of a syllable or syllables