apropos of something
From Longman Dictionary of Contemporary Englishapropos of somethingapropos of something formalABOUTused to introduce a new subject that is related to something just mentioned He had nothing to say apropos of the latest developments.apropos of nothing (=not relating to anything previously mentioned) Apropos of nothing, he suddenly asked me if I liked cats! → aproposExamples from the Corpusapropos of nothing• Douglas paused and then, apropos of nothing , announced, "We could have been in New York by now."