1) Usually a hedging-bill, that is a heavy, thick knife with a hooked end, used for laying or pruning hedges.
1644 Item two strikeingbills one paire of chopping billes, Lepton
1699 one pair of chopping bills, Slaithwaite. The implement had a distinctive shape and this gave rise to the field-name Chopping Bill Close, found in several parishes, the earliest in Lepton in 1720. In connection with tanners it is likely to have been a knife for chopping bark: 1681 a waggon with bark chopt & unchopt, Selby
1686 1 working tree & working knife, 1 choping bill, 1 bark skep, Selby.