apropos is an interactive autoloaded compiled Lisp function in `apropos.el'.

It is bound to <menu-bar> <help-menu> <search-documentation> <find-any-object-by-name>.

(apropos PATTERN &optional DO-ALL)

Show all meaningful Lisp symbols whose names match PATTERN.
Symbols are shown if they are defined as functions, variables, or
faces, or if they have nonempty property lists.

PATTERN can be a word, a list of words (separated by spaces),
or a regexp (using some regexp special characters). If it is a word,
search for matches for that word as a substring. If it is a list of words,
search for matches for any two (or more) of those words.

With C-u prefix, or if `apropos-do-all' is non-nil,
consider all symbols (if they match PATTERN).

Returns list of symbols and documentation found.