delay time (1) (general) (td)

The time interval between a reference point on one waveform and a reference point on another waveform.

(2) (between input and output): The time interval between a transition at an input and a resultant change at an output.

(3) (of an integrated circuit) (td, tdr, and tdf): The time interval between a step-function change of the input signal level and the instant at which the magnitude of the output signal passes through a specified value (normally 10% for tdr or 90% for tdf) close to its initial value. (Ref. IEC 748‑3.)

(4) (of a transistor) (td): (A) The time interval from the point at which the leading edge of the input pulse has reached 10% of its maximum amplitude to the point at which the leading edge of the output pulse has reached 10% of its maximum amplitude.

(B) Synonym for "current delay time, tdi".

References: 

JESD77-B, 2/00
JESD99B, 5/07
JESD100-B, 12/99

JESD77-B, 2/00

JESD99B, 5/07

JESD10, 9/81

JESD77-B, 2/00