apropos locate commands by keyword lookup

Search the whatis database for strings, see the section called "The whatis and apropos commands".

Search the whatis database for strings, see Section 2.3.3.2.

By the way; to the purpose; suitably to the place or subject; -- a word used to introduce an incidental observation, suited to the occasion, though not strictly belonging to the narration.

by the way; "apropos, can you lend me some money for the weekend?"

Opportunely or opportune; seasonably or seasonable.

at an opportune time; "your letter arrived apropos"

An opportune moment to launch an action.

to the point or purpose; appropriate

of an appropriate or pertinent nature