up tack

The up tack or falsum (⊥, \bot in LaTeX, U+22A5 in Unicode) is a constant symbol used to represent:

• The bottom element in lattice theory
• The bottom type in type theory
• A logical constant denoting contradiction in logic (false)

The glyph of the up tack appears as an upside-down tee symbol, and as such is sometimes called eet (the word "tee" in reverse).