Mathematical symbol displayed on a blackboard

• Del Shannon, a Blackfoot at heart
• Triangular symbol composer of 1 down set up

Wikipedia Word definitions in Wikipedia
Nabla may refer to one of the following: the nabla symbol ∇ the vector differential operator, also called del , denoted by the nabla Nabla, tradename of a type of rail fastening system (of roughly triangular shape) Nabla (moth) , a genus of moth Nabla (instrument) ...

Wiktionary Word definitions in Wiktionary
n. 1 (Hebrew) A Hebrew stringed instrument. 2 (context analysis English) The symbol ∇, used to denote the gradient operator.

The Collaborative International Dictionary Word definitions in The Collaborative International Dictionary
del \del\ n. (Math.) a differential operator which, operating on a function of several variables, gives the sum of the partial derivatives of the function with respect to the three orthogonal spatial coordinates; -- also called the gradient or grad . It ...