su·pine (spīn′, s-pīn)
1. Lying on the back or having the face upward.
2. Having the palm upward. Used of the hand.
3. Marked by or showing lethargy, passivity, or blameworthy indifference: "No other colony showed such supine, selfish helplessness in allowing her own border citizens to be mercilessly harried" (Theodore Roosevelt).
In Latin grammar, a verbal noun used in only a few syntactic constructions and occurring in only two cases, an accusative in -tum or -sum and an ablative in -tū or -sū. The accusative form of the supine is sometimes considered to be the fourth principal part of the Latin verb.
[Middle English supin, Latin verbal noun, from Late Latin supīnum (verbum), (verb) lying on its back, (verb) going back, neuter of Latin supīnus; see upo in the Appendix of Indo-European roots.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
The American Heritage Dictionary Blog
Check out our blog, updated regularly, for new words and revised definitions, interesting images from the 5th edition, discussions of usage, and more.