Definition of terne:
(adj) :
Colourless, drab, dull.
(n) :
(also attributively) An alloy coating made of lead and tin (or, more recently, zinc and tin), often with some antimony, used to cover iron or steel.
(n) :
Synonym of terneplate (“thin iron or steel sheeting coated with this alloy”).
(n) :
Obsolete spelling of tern (“any of various seabirds of the subfamily Sternidae (of the family Laridae) that are similar to gulls but are smaller and have a forked tail”). [Any of various seabirds of the subfamily Sterninae (of the family Laridae) that are similar to gulls but are smaller and have a forked tail.]