Find the word definition

Wiktionary
vertical bar

n. 1 (context computing English) The ASCII character at the decimal position of 124, depicted as (unsupported: pipe) or ¦; 2 (context mathematics English) represents an absolute value (e.g. |x|) 3 (context mathematics English) norms (e.g. ||(x_1,x_2)||) 4 (context mathematics English) set definitions (e.g. {x|x) 5 (context mathematics English) conditional probability (e.g. P(X|Y)) 6 (context mathematics English) divisibility (e.g. a | b) 7 (context computing English) (non-gloss definition: a symbol which, in Unix, is used as a pipe) 8 (context computing English) (non-gloss definition: a symbol which, in regular expressions, indicates an alternation)

Wikipedia
Vertical bar

The vertical bar ( | ) is a computer character and glyph with various uses in mathematics, computing, and typography. It has many names, often related to particular meanings: Sheffer stroke (in logic), verti-bar, vbar, stick, vertical line, vertical slash, bar, obelisk, or pipe. On a QWERTY keyboard, the combination of the "shift" key and the backslash "\" key outputs the character "|". Other keyboard layouts may use different combinations to output the vertical bar.