forget about unpleasant things that have happened in the past.

There is a feeling here that we should let bygones be bygones and move on to more important things.

Usage notes: sometimes used in the form bygones are bygones:

What is past history is history, what is done is finished, and bygones are bygones.

• sink without trace
• sink your teeth into
• sink your teeth into something
• sin tax
• siphon off
• siphon off something
• sit around on backside
• sit around on your backside
• sit back
• sit back and
• sit back and do something
• sit by
• sit by and
• sit by and do something
• sit idly by
• sit idly by and
• sit idly by and do something
• sit in
• sit in for
• sit in for someone
• sit in judgment
• sit in judgment of
• sit in judgment of someone
• sit in judgment of something
• sit in judgment on