Noun
(fishing) Initialism of giant trevally.
(fishing) Initialism of golden trevally.
(motor racing) Initialism of grand tourer.
(endocrinology) Initialism of gain of thyroid.
Gt (plural Gts)
(music, Japan) Abbreviation of guitar (of a rock band)
gt (plural gtt)
(medicine, dated) drop (as a measurement in medical prescriptions)