Definitions for hypothesishaɪˈpɒθ ə sɪs, hɪ-; -ˌsiz

Random House Webster's College Dictionary

hy•poth•e•sis^*haɪˈpɒθ ə sɪs, hɪ-; -ˌsiz(n.)(pl.)-ses

a provisional theory set forth to explain some class of phenomena, either accepted as a guide to future investigation
Category: Philosphy, Biology, Physics
Ref: ( working hypothesis )
a proposition assumed as a premise in an argument.
the antecedent of a conditional proposition.
a mere assumption or guess.

^* Syn: See theory.

Origin of hypothesis:

1590–1600; < Gk hypóthesis basis, supposition = hypo(ti)thé(nai) to assume, suppose ( hypo- hypo - + tithénai to put, place) + -sis -sis

hy•poth′e•sist(n.)

Princeton's WordNet

hypothesis(noun)
a proposal intended to explain certain facts or observations
hypothesis, possibility, theory(noun)
a tentative insight into the natural world; a concept that is not yet verified but that if true would explain certain facts or phenomena
"a scientific hypothesis that survives experimental testing becomes a scientific theory"; "he proposed a fresh theory of alkalis that later was accepted in chemical practices"
guess, conjecture, supposition, surmise, surmisal, speculation, hypothesis(noun)
a message expressing an opinion based on incomplete evidence

Kernerman English Learner's Dictionary

hypothesis(noun)ɪˈpɒθ ə sɪs, hɪ-
an explanation that has not yet been scientifically tested
a hypothesis based on previous experiments

Wiktionary

hypothesis(Noun)
Used loosely, a tentative conjecture explaining an observation, phenomenon or scientific problem that can be tested by further observation, investigation and/or experimentation. As a scientific term of art, see the attached quotation. Compare to theory, and quotation given there.
hypothesis(Noun)
An assumption taken to be true for the purpose of argument or investigation.
hypothesis(Noun)
The antecedent of a conditional statement.

Origin: Recorded since 1596, from hypothese, from hypothesis, from ὑπόθεσις, literally “a placing under”, itself from ὑποτίθημι, from ὑπό + τίθημι.

Webster Dictionary

Hypothesis(noun)
a supposition; a proposition or principle which is supposed or taken for granted, in order to draw a conclusion or inference for proof of the point in question; something not proved, but assumed for the purpose of argument, or to account for a fact or an occurrence; as, the hypothesis that head winds detain an overdue steamer
Hypothesis(noun)
a tentative theory or supposition provisionally adopted to explain certain facts, and to guide in the investigation of others; hence, frequently called a working hypothesis