a proposal intended to explain certain facts or observations
"The scientist presented her hypothesis that climate change was causing the recent shift in migration patterns."
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"
a message expressing an opinion based on incomplete evidence
"The manager's hypothesis that the new software would boost sales was quickly proven wrong when user complaints flooded in."
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.
"The researcher proposed a hypothesis that increased sunlight would accelerate plant growth, which she planned to verify through controlled experiments."
In plain English: A hypothesis is an educated guess that you make before doing any experiments to see if it turns out true.
"The scientist presented her hypothesis that plants grow faster when they receive more sunlight."
Usage: A hypothesis is a specific type of educated guess proposed to explain an observed phenomenon and must be testable through experimentation. Do not confuse it with a general theory, as the former serves only as a starting point for investigation rather than a proven explanation.
The word hypothesis entered English in 1596 via Middle French and Late Latin, originally describing a "base" or foundation for an argument. It derives from the Ancient Greek term meaning literally "a placing under," which comes from verbs signifying to set something before someone as a suggestion.