are letters that make 'TDT'
are words within 'TDT'
1 possible definitions for 'TDT'
Under this definition, tdt is a noun and has the following properties:
terrestrial time, TT, terrestrial dynamical time, ephemeris time
have the same meaning as 'TDT'
'TDT' can be a type of time unit, unit of time.
'TDT' can be a category of astronomy, uranology.