\STOH-ik\, noun: 1. (Capitalized). A member of a school of philosophy founded by Zeno holding that one should be free from passion, unmoved by joy or grief, and should submit without complaint to unavoidable necessity. 2. Hence, one who is apparently or professedly indifferent to or unaffected by pleasure or pain, joy or grief.
My dog Darth was good at acting stoic whenever we bathed him, but the look in his eyes always gave away how much he hated it.