Merriam-Webster Collegiate Dictionary - stoic

 I. noun  Etymology: Middle English, from Latin ~us, from Greek stoikos, literally, of the portico, from Stoa (Poikile) the Painted Portico, portico at Athens where Zeno taught  Date: 14th century  1. capitalized a member of a school of philosophy founded by Zeno of Citium about 300 B.C. holding that the wise man should be free from passion, unmoved by joy or grief, and submissive to natural law  2. one apparently or professedly indifferent to pleasure or pain  II. adjective  or ~al  Date: 15th century  1. capitalized of, relating to, or resembling the Stoics or their doctrines Stoic logic  2. not affected by or showing passion or feeling; especially firmly restraining response to pain or distress a ~ indifference to cold  Synonyms: see impassive  • ~ally adverb