Cowardly or timid, like a duck which is considered a timid bird; lacking courage or bravery.
Compound of 'duck' and 'hearted' (having a certain kind of heart or courage). Ducks were stereotyped as fearful birds, making this a natural insult term for cowardice.
This insult connects to medieval and Shakespearean times when people used animal characteristics as shortcuts for human traits—'duck-hearted' joins 'lion-hearted' and 'chicken-hearted' as animal-based personality labels.
Complete word intelligence in one call. Free tier — 50 lookups/day.