Meaning

Usually refers to one’s family. Sometimes used (as in Shakespeare’s original) to denote all living creatures.

Origin

From Shakespeare’s Hamlet.

Clown: I have been, madam, a wicked creature, as you and all flesh and blood are; and, indeed, I do marry that I may repent. —Flesh and Blood (The Prhase Finder)

Er, no, that’s not from Hamlet. It’s from All’s Well That Ends Well (I.iii).

I love quirky online databases, too, but here’s one example of why failing to confirm what you find online can lead to trouble. The consequences in this case are negligible, but imagine somebody going online to make health-related decisions!