slip vs slip by

slip is a noun but slip by is not a noun.

Word	Noun	Adjective	Verb	Adverb
slip	Yes	No	Yes	No
slip by	No	No	Yes	No

slip (noun)	slip by (noun)
a flight maneuver; aircraft slides sideways in the air
a socially awkward or tactless act
the act of avoiding capture (especially by cunning)
an unexpected slide
a minor inadvertent mistake usually observed in speech or writing or in small accidents or memory lapses etc.
a woman's sleeveless undergarment
bed linen consisting of a cover for a pillow
artifact consisting of a narrow flat piece of material
a small sheet of paper
a slippery smoothness
an accidental misstep threatening (or causing) a fall
a place where a craft can be made fast
a young and slender person
a part (sometimes a root or leaf or bud) removed from a plant to propagate a new plant through rooting or grafting
potter's clay that is thinned and used for coating or decorating ceramics

slip (verb)	slip by (verb)
fall to a lower standard	for time to move forward
move out of position
insert inconspicuously or quickly or quietly
to make a mistake or be incorrect
pass out of one's memory
move obliquely or sideways, usually in an uncontrolled manner
move stealthily
move easily
move smoothly and easily
cause to move with a smooth or sliding motion
pass on stealthily