lacto-

a combining form meaning “milk,” used in the formation of compound words (lactometer); specialized in chemical terminology to mean “lactate,” or “lactic acid.”.

Also, lacti-; especially before a vowel, lact-.

Origin

< Latin lact- (stem of lac milk) + -o-

British Dictionary definitions for lacto-

lacto-

combining form

indicating milk: lactobacillus

Word Origin

from Latin lact-, lac milk

Word Origin and History for lacto-

before vowels, lac-, word-forming element meaning "milk," from Latin lac (genitive lactis) "milk," from PIE root *glakt- (see lactation).

lacto- in Medicine

lacto- or lact- or lacti-
pref.

Milk: lactoglobulin.
Lactose: lactase.
Lactic acid: lactate.