Idioms with HEART

at heart
fundamentally; in reality
He has a lot of friends, but he is a private person at heart.

by heart
from memory; using only your memory
They knew all the songs by heart

lose heart
to become discouraged
She never lost heart, even in the face of difficulties.

have a heart
to be kind, sympathetic, generous, etc.
Please have a heart and give them another chance.

not have the heart
to not be able to do something because it seems cruel
I didn’t have the heart to tell him the truth.