- (geometry) A triangle.
- A triangle with vertices named A, B, and C in order.
- (astrology) The symbol for trine.
- (entomology) A symbol to indicate that an illustration represent the underside of a specimen.
- See Δ for the Greek capital letter delta.
- See ∆ for the increment symbol.
- (computing, dated) ISO 2047 symbol for Space
- not so good
- (accounting) minus, equivalent of parentheses in English