The Old English word "twelf" ≈ "twelve" comes from "two" and "left". That is, there are two left when ten is taken away. The English word "twelve" is related to the German word "zwölf" ≈ "twelve".

The word for "left" meant the same thing as "lacks".

The English word "dozen" comes from French which comes from the Latin word "duodecim" ≈ "twelve" which means, literally, "two ten" or "two" plus "ten". The modern Greek word "δώδεκα" (THO-theh-ka) ≈ "twelve" comes from the same concept. The German word "dutzend" ≈ "dozen" comes from Latin as does the Russian word "дюжина" (du-schi-na) ≈ "dozen".

By the time I tell you 12 boring jokes about eggs you will be a "dozen".