the word transpire entered english in the late middle english period from medieval latin transpirare, a compound of the latin elements trans- and spirare. literally meaning "to breathe across or through," it was first used in a physiological sense to describe the passage of vapour or moisture through the pores of a surface, such as a plant's leaves. this literal sense of something passing through a barrier provided a logical metaphor for facts or information gradually becoming known, as if seeping out into public awareness. the later, more general north american usage meaning "to happen" developed as an extension of this idea of events coming to light or becoming apparent.

Structure: trans (across) + spire (breathe) trans (latin preposition and prefix, meaning "across, through, beyond"); spire (from latin spirare, meaning "to breathe")