English could

← Old English cūþe (inherited)

← Old English cunnan (mention)

← Old English cūþ (mention)

← English couth (mention)

← Middle English coude (inherited)

← Middle English couthe (mention)

← Middle English cuthe (mention)

← Proto-Indo-European *ǵneh₃- (root)

→ English might (link)

→ English couldn't (suffix)

→ English cud (mention)

→ English couth (doublet)

→ English could've (suffix)

→ English couldest (suffix)

→ English couldnae (compound)

→ English chud (prefix)

→ English chud (mention)

→ Portuguese como (link)