Plural of adder; venomous or non-venomous snakes of the viper family, particularly common in Europe and Asia.
Old English 'ædre' or 'nædre,' related to Old Norse 'naðr.' The 'n' was lost over time through misdivision ('a nadder' became 'an adder'), a process called reanalysis in linguistics.
The word 'adder' is a perfect example of how English changes through mishearing—people originally said 'a nadder' but gradually said 'an adder' until everyone forgot it ever had an 'n'!
Complete word intelligence in one call. Free tier — 50 lookups/day.