∅

See also: ∅-, -∅, -∅-, Ø [U+00D8 LATIN CAPITAL LETTER O WITH STROKE], ⌀ [U+2300 DIAMETER SIGN], and ø [U+00F8 LATIN SMALL LETTER O WITH STROKE]

∅ U+2205, ∅ EMPTY SET ← ∄ [U+2204] Mathematical Operators ∆ → [U+2206]

⦰ U+29B0, ⦰ REVERSED EMPTY SET ← ⦯ [U+29AF] Miscellaneous Mathematical Symbols-B ⦱ → [U+29B1]

Translingual

Etymology

The set-theoretic meaning of this symbol was introduced by the Bourbaki group in their treatise Éléments de mathématique. André Weil has said in his autobiography that he based it on the Norwegian letter Ø.

Symbol

∅

1. (set theory) A set with no elements: the empty set.

   Synonyms: { }, {}

2. (linguistic morphology) A null morpheme; a theoretical morpheme used in models of linguistic analysis to represent the absence of a morpheme where one might otherwise be expected.

See also

• ∅- (the zero prefix)
• -∅ (the zero suffix)
• -∅- (a zero prefix in Navajo)
• null determiner

Vietnamese

Etymology

From the empty set symbol.

Adjective

∅

1. Abbreviation of trống (“empty”).