1. (

• hypothesis

) a proposal intended to explain certain facts or observations ;

2. (

• hypothesis ,
• possibility ,
• theory ,

) 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" ;

3. (

• guess ,
• conjecture ,
• supposition ,
• surmise ,
• surmisal ,
• speculation ,
• hypothesis ,

) a message expressing an opinion based on incomplete evidence ;