Medical Dictionary
second messenger
noun
Medical Definition of SECOND MESSENGER
: an intracellular substance (as cyclic AMP) that mediates cell activity by relaying a signal from an extracellular molecule (as of a hormone or neurotransmitter) bound to the cell's surface—compare first messenger
Seen & Heard
What made you want to look up second messenger? Please tell us where you read or heard it (including the quote, if possible).