Currently the tag definition has 35 questions. No tag wiki excerpt is available. The dictionary definition of "definition" (how meta...) is:
a statement of the exact meaning of a word, especially in a dictionary.
6 of these questions are also tagged cc-cedict (and incidentally all were asked by @Becky). In this case, it's clear enough that [definition] is related to a CC-CEDICT entry.
Among the remaining 29 questions not tagged [cc-cedict], it appears what most of them are asking is the meaning of some term. In those cases, the tag [definition] seems kinda overlapping with [meaning] / [meaning-in-context], or [difference], or possibly [translation].
Since there are 6 questions tagged only with definition, we can maybe examine those first:
Why/how does 说 mean update in 下次再说?. I would tag this [meaning-in-context]
What is the difference between 國語 and 普通話?. I would tag this [difference]. Possibly [taiwan], possibly [usage].
Is there a word for 1/3?. Possibly [word], surely not [definition].
How is “戚” Being Used as a Standalone Verb to Mean “Feel”? [closed] (rightfully closed)
What is this character used for: 夰 [characters] seems appropriate, and exhaustive.
What does 旧币 refer to exactly?. [definition] is actually appropriate.
It seems there are a few instances where the tag is actually useful and/or helps disambiguate the scope of the question. So synonyms and burnination might be unwarranted. Instead some careful retagging could be beneficial.
What do you think?
EDIT:
I proposed a tag synonym from [definition] to [meaning], please feel free to vote on that