Write margin
Beginner
How easily a memory cell takes a new value when you write to it.
Novice
How much room is left when writing an SRAM cell: how far below the switching point the bit line manages to pull the stored 1. If the cell’s pull-up is too strong, the node never gets low enough and the write fails.
Expert
Measured several ways: the write noise margin (smallest square between the write-mode VTCs), the highest bit-line voltage that still flips the cell, or the word-line voltage margin. It degrades at fast-PMOS/slow-NMOS corners and low ; write assists such as a boosted word line restore it.
Explained in Memory cells (Transistors).
See also: Pull-up ratio, Static noise margin (SNM).