What is Greek and Latin root for one?

There isn't one single perfect Greek or Latin root for "one." The concept is expressed differently depending on the nuance. Here are some options and why they aren't a direct, single equivalent:

* Greek: The closest would be μόνος (monos), meaning "single," "alone," or "only." This emphasizes singularity rather than the numerical value. There's no single Greek root directly translating to the cardinal number "one" in the same way "uni-" functions in Latin-based words.

* Latin: The root *uni-* (as in "unilateral," "uniform," "unique") is probably the closest. However, it carries connotations of "single" or "one of a kind," not simply the numerical value. Latin also uses "unus" as the word for "one," but that's a full word, not a root that combines with other elements to create new words in the same way *uni-* does.

In short, while *uni-* (Latin) gets closest in terms of forming compound words, neither language has a single root that perfectly captures the pure numerical concept of "one" as a building block for other words in the same way roots for higher numbers might exist.