apropos

definition: introducing a different topic
example:
speech part: adverb
synonyms: by the way
definition: at an opportune time
example: your letter arrived apropos
speech part: adverb
synonyms: seasonably timely well-timed opportunely
definition: of an appropriate or pertinent nature
example:
speech part: adjective
synonyms:

apropos is explained and pronounced

How apropos is being used?