Initialism of atomic buffalo turd.
"The new acronym ABT stands for Atomic Buffalo Turd, which is a silly nickname some kids use for their pet rock."
In plain English: Abt is an old-fashioned spelling of about that means approximately or roughly when talking about time, numbers, or amounts.
"During the game, the crowd watched as the umpire made an important call involving the abt."
all but thesis: A description of the status of a masters, doctoral, or (infrequently) undergraduate student who has completed all degree requirements except the culminating thesis.
"The senior research assistant is an abt candidate awaiting final approval on her dissertation to officially graduate with her doctorate."
"The abt condition caused several delays in our travel plans today."
Usage: Use this term exclusively in academic contexts to describe students who have finished every requirement except their final thesis. It is not used for general situations where something is incomplete.
Abbreviation of about.
"The meeting is scheduled to start at 3 p.m., but it might run a bit longer, so please arrive by 2:45 pm abt the time you planned."