תְּכֵלֶת tᵉkêleth (H8504)

the cerulean mussel, i.e. the color (violet) obtained therefrom or stuff dyed therewith

1) violet, violet stuff 1a) violet thread 1b) violet stuff or fabric 2) (TWOT) blue (covering spectrum from brilliant red through deep purple)

probably for שְׁחֶלֶת (H7827);