WordNet (r) 3.0 (2006):

TT
    n 1: (astronomy) a measure of time defined by Earth's orbital
         motion; terrestrial time is mean solar time corrected for
         the irregularities of the Earth's motions [syn:
         terrestrial time, TT, terrestrial dynamical time,
         TDT, ephemeris time]
    2: a republic in the western central Pacific Ocean in
       association with the United States [syn: Palau, Republic
       of Palau, TT]
    3: a country scattered over Micronesia with a constitutional
       government in free association with the United States;
       achieved independence in 1986 [syn: Micronesia, Federated
       States of Micronesia, TT]

The Free On-line Dictionary of Computing (30 December 2018):

tt

    The country code for Trinidad and Tobago.

   (1999-01-27)