- (mathematics) A (path-dependent, inexact) differential.
- (mathematics) A small number, usually accompanied by ε.
- For any , there is a …
- (mathematics) Kronecker delta or Dirac delta.
- Lower case delta (δέλτα), the fourth letter of Greek alphabet. It represented in Ancient Greek a voiced dental plosive: /d/ and in modern Greek a voiced dental fricative: /ð/. It is preceded by γ and followed by ε.
- δις (dis)
- δις (dis, “Miss”)