lie by

lay by

To save or reserve something, especially money, for future use. In this usage, a noun or pronoun can be used between "lay" and "by." If you can even lay by $100 a month, it will go a long way toward paying off the loan. Don't throw away all that scrap metal—we can lay it by for our next project.
See also: by, lay

lie by

1. verb, dated To rest; to not move or put forth physical effort. Primarily heard in UK. Your body needs time to recover from this illness, so for now you should just lie by.
2. verb, dated To not be acted upon; to be left undisturbed. Primarily heard in UK. I think we should let the issue lie by awhile before making any further decisions.
3. noun A section of paved road adjacent to a highway in which cars can stop, as in emergencies. Often spelled with a hyphen. Primarily heard in UK. Please pull over onto the lie-by while you wait for assistance.
See also: by, lie
Farlex Dictionary of Idioms.

lay by

v.
To save something for future use: After she had laid by a good sum of money, the lawyer bought a new condo for use as her office. The mechanic packed up his tools and laid them by for the next project.
See also: by, lay
The American Heritage® Dictionary of Phrasal Verbs.
See also:
  • lay aside (something) for (someone or something)
  • lay aside for
  • lay over
  • lay back
  • lie back
  • lay away
  • lay (something) on (someone or something)
  • lay on
  • lay something on someone
  • dream away