/ pɔːˈtentəs; NAmE pɔːrˈt-/ adjective
1.
( literary ) important as a sign or a warning of sth that is going to happen in the future, especially when it is sth unpleasant :
a portentous sign
2.
( formal , disapproving ) very serious and intended to impress people
SYN pompous :
a portentous remark
► por·tent·ous·ly adverb
► por·tent·ous·ness noun [ U ]