a tentative theory about 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 proposal intended to explain certain facts or observations
the convergence of two parallel railroad tracks in a narrow place; the inner rails cross and run parallel and then diverge so a train remains on its own tracks at all times
resist or confront with resistance; "The politician defied public opinion"; "The new material withstands even the greatest wear and tear"; "The bridge held"
elude, especially in a baffling way; "This behavior defies explanation"