別に to mean "not particularly"


I hear 別に used as "not in particular", did this usage come about just directly
from the meaning of "separately"? So when used, it means that someone has a
separate interest, like, etc. and hence they don't particularly have the
interest, or share the like?




No, this negative expression means "Not really", "I'm not interested", "I
don't care", etc.

I think this 「別に…」 is the shortened form of "別に言いたいことはない" or "別にそういうわけではない",
and 別に here roughly corresponds to _particularly_.

Something positive, like "これとは別のものが好きです" or "私はこれとは別に、言いたいことがあります" is not what
the speaker want to say.

