It was symbolic of how sin and evil had blotted out the life of Christ.
On official maps, the western half of the city was blotted out—figuratively erased from the world of the living.
In Deuteronomy 26:17-19 we are told of the Amalekites, a people so heinous, so evil, that their memory should be “blotted out.”
late 14c., originally "blemish," perhaps from Old Norse blettr "blot, stain," or from Old French blot, variant of bloc "block," or blestre "blister, lump, clump of earth."
early 15c., "to make blots;" mid-15c. "to blot out, obliterate" (words), from blot (n.). Related: Blotted; blotting.
The Northern, Southern, or Western blot analyses.
a stain or reproach (Job 31:7; Prov. 9:7). To blot out sin is to forgive it (Ps. 51:1, 9; Isa. 44:22; Acts 3:19). Christ's blotting out the handwriting of ordinances was his fulfilling the law in our behalf (Col. 2:14).