look vs look after

look is a noun but look after is not a noun.

Word	Noun	Adjective	Verb	Adverb
look	Yes	No	Yes	No
look after	No	No	Yes	No

look (noun)	look after (noun)
the act of directing the eyes toward something and perceiving it visually; look
physical appearance
the feelings expressed on a person's face
the general atmosphere of a place or situation and the effect that it has on people

look (verb)	look after (verb)
to physically appear a certain way to another individual or group	keep under careful scrutiny
look forward to the probable occurrence of
have faith or confidence in
convey by one's expression
perceive with attention; direct one's gaze towards; look
give a certain impression of being something or having a certain aspect
search or seek
take charge of or deal with
be oriented in a certain direction, often with respect to another reference point; be opposite to
accord in appearance with