The symbol ∇, used to denote the gradient operator. (noun)
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Use "nabla" in a sentence
"I once wrote "nabla" (an Assyrian harp, term was introduced by the very Anglo Saxon Peter Tait) and I got a very antisemitic reaction to the extent that Jews want to turn everything into something Jewish, even math symbols."
"The standard quantization is that momentum p is replaced with the operator (hbar/i) nabla (nabla is a directional derivative) and E = ihbar &/& t (& = partial)."
"The real part is the instanton component that is a nabla S nabla I, reflecting the small quantum aspect of the spacetime — eg a WKB type of approximation."