n (British) The intermediate light in a set of three traffic lights, the illumination of which indicates that drivers should stop short of the intersection if it is safe to do so.
n (context|biology|genetics|biochemistry) The stop codon (nucleotidetriplet) "UAG", or a mutant which has this stop codon at a premature place in its DNA sequence.
a Of a brownish yellow colour, like that of most amber.
v (transitive) To perfume or flavour with ambergris.