n. pl. hy·poth·e·ses (-sēz′)
1. A tentative explanation for an observation, phenomenon, or scientific problem that can be tested by further investigation.
2. Something taken to be true for the purpose of argument or investigation; an assumption.
3. The antecedent of a conditional statement.
[Latin, subject for a speech, from Greek hupothesis, proposal, supposition, from hupotithenai, hupothe-, to suppose : hupo-, hypo- + tithenai, to place; see dhē- 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.