Portend is defined as to be a warning or signal of.
(verb)When rain clouds warn of rain, this is an example of a time when the clouds portend rain.
See portend in Webster's New World College Dictionary
transitive verb
Origin: ME portenden < L portendere < por-, akin to per, through + tendere, to stretch: see thin
See portend in American Heritage Dictionary 4
transitive verb por·tend·ed, por·tend·ing, por·tends
Origin:
Origin: Middle English portenden
Origin: , from Latin portendere; see ten- in Indo-European roots
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