Here's a breakdown:
* Mono- means "one"
* Syllable refers to a unit of pronunciation that typically contains one vowel sound.
So, a monosyllabic word is a short, single-sound word. Examples include:
* cat
* dog
* run
* tree
* love
The term "monosyllabic" can also be used to describe a person's communication style. Someone who is monosyllabic may be:
* Concise
* Curt
* Brief
* Unwilling to elaborate
It can imply a lack of interest, or even rudeness, depending on the context.