1
general::
Remember or consider on reflection. For example, Come to think of it, I've got to send in my order now, or I was going to lend him a saw, but come to think of it, he already has one. [First half of 1800s]
American Heritage Idioms
2
general::
Phrase(s): come to think of it
I just remembered. • Come to think of it, I know someone who can help. • I have a screwdriver in the trunk of my car, come to think of it.
McGrawhill's American Idioms And Phrasal Verbs