lapse vs slip by

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

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

As verbs, lapse and slip by are synonyms defined as:

Other synonyms of lapse include elapse, glide by, go along, go by, pass, slide by, slip away.

lapse (noun)	slip by (noun)
a mistake resulting from inattention
a failure to maintain a higher state
a break or intermission in the occurrence of something

lapse (verb)	slip by (verb)
go back to bad behavior	for time to move forward
drop to a lower level, as in one's morals or standards
end, at least for a long time
for time to move forward
pass into a specified state or condition; sink into
let slip