"to presage, foreshadow, signify in advance," early 15c., portenden, from Latin portendere "foretell, reveal; point out, indicate," originally "to stretch forward," from por- (variant of pro-; see pro-) "forth, forward" + tendere "to stretch, extend," from PIE root *ten- "to stretch." The literal Latin sense "stretch forth, extend" was occasional in English 17c.-18c. Related: Portended; portending.
