Apropos of nothing, he suddenly asked me if I liked cats!aproposap‧ro‧pos /ˌæprəˈpəʊ, ˈæprəpoʊ $ -poʊ/ adverb formal 
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!
WORD ORIGINapropos
Origin:
1600-1700 French à propos ‘to the purpose’EXAMPLES FROM THE CORPUS
- Or more apropos, one bird splat spreads forevermore.
- The song feels right, apropos to a midnight jaunt, a walk with a good friend.
COLLOCATIONS FROM THE ENTRY
(=not relating to anything previously mentioned) Apropos of nothing, he suddenly asked me if I liked cats!
Apropos of nothing, he suddenly asked me if I liked cats!PHRASES FROM THE ENTRY
apropos of something used to introduce a new subject that is related to something just mentioned: - She had nothing to say apropos of the latest developments.
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!