by·gones 
/ˈbaɪˌgɑ:nz/ noun
/ˈbaɪˌgɑ:nz/ noun Meaning:
let bygones be bygones
: to forgive someone for something done to you or for a disagreement with you and forget about it
▪ I know we've had our fights over the years, but I think it's time we let bygones be bygones.
▪ I know we've had our fights over the years, but I think it's time we let bygones be bygones.
