core
/kɔːr/·코어·noun
the central or most important part
LatinCEFR B1
Root
Latin 'cor' (heart)
Latin cor (heart) → Old French cuer → Middle English core (innermost part of fruit) → Modern English
In a word
core began as Latin cor (heart). The middle of an apple, the middle of a team, the middle of a problem — all of them: core. The same cor lives in courage (heart-state) and record (re-cor, "back to the heart"). "Mark it on your heart" became "record it" — that's where the verb starts.
Examples
The core of the problem is poor communication.
She is part of our core team.
Apples have a core full of seeds.
Related
courageencouragediscouragecordialrecord