The story
From pointing (“placement of marks in the text to indicate the syllables on which the chant should progress to the next note”) + mark.
Etymology from Wiktionary, CC BY-SA 4.0.
pointing mark
Today it means: In Anglican chant, a mark in the text which corresponds to a barline in the chant, which indicates the syllables on which the chant changes note; typically a vertical line ( | ) or apostrophe ( ' ). Full definition →