This phrase formerly meant "by fair means or foul", although now it often (especially in the
U.K.) means simply "by whatever necessary means".
The first recorded use is by
John Wycliffe in
Controversial Tracts (circa 1380).
Theories of origin include:
- A law or custom in mediaeval England that allowed peasants to take as firewood from the King's forests any deadwood that they could reach with a shepherd's crook and cut off with a reaper's billhook
- Rhyming words for "direct" (reachable with a long hook) and "indirect" (roundabout)
- Beginners' writing exercises, where letters have hooks and brackets are "crooks"
- From "Hook" and "Crook", the names of headlands on either side of a bay north of Waterford, Ireland, referring to a captain's determination to make the haven of the bay in bad weather using one headland or the other as a guide.
Source: Mark Israel, 'Phrase Origins: "by hook or by crook"', The alt.usage.english FAQ file. Slightly modified and formatted by me.