LDT may stand for: Laterodorsal tegmental nucleus, a nucleus in the brain stem Laboratory developed test, in vitro diagnostics Labordatenträger, a German xDT format to transfer laboratory tests Large deviations theory, field of probability theory Learning Design and Technology, an academic program Lexical decision task in psychology experiments Lightning Data Transport, later HyperTransport computer bus Local Descriptor Table, an x86 data structure Telbivudine or LdT, a drug for hepatitis B Computer file extension for EULUMDAT