蛇だ足そく

noun, noun which may take the genitive case particle 'no'

redundancy; superfluity; useless addition

Refers to something unnecessary that detracts from the whole, like adding legs to a drawing of a snake. Often used in the phrase 蛇足ながら (although it may be redundant).

• その説せつ明めいは蛇だ足そくだ。

  That explanation is redundant.

• 蛇だ足そくながら、もう一ひと言こと付つけ加くわえさせてください。

  At the risk of being redundant, let me add one more thing.