Per-

Borrowing from la per and per-.

Full definition of per-

Prefix

1. (non-productive) In verbs: denoting the sense "through", as in perforate.
2. (non-productive) In verbs: denoting the sense "thoroughly", as in perfect.
3. (non-productive) In verbs: denoting the sense "to destruction", as in pervert.
4. (non-productive) In adjectives and adverbs: denoting the sense "extremely", as in perfervid.
5. (chemistry) Forming nouns and adjectives denoting the maximum proportion of one element in a compound, as in peroxide.
6. (chemistry) Added to the name of an element in a polyatomic ion denote the number of that element (usually four).

Derived terms

Borrowing from fro per (modern French par).

Prefix

1. (non-productive) Denoting the sense "by" or "per", as in perchance or perhaps.----