del
/del/noun
1- Mathematics an operator used in vector analysis. (Symbol: ▽)【数】倒三角形, 戴尔（矢量算子）（符号：▽）。
1.1
- del is defined as ið/ðx+jð/ðy+kð/ðz, where i, j, and k are vectors directed respectively along the Cartesian axes x, y, and z.▽定义为ið/ðx+jð/ðy+kð/ðz, 其中i, j和 k分别为笛卡尔轴x、 y和z上表示的矢量。
词源
early 20th cent.: abbreviation of DELTA1， from the representation of the operator as an inverted capital delta.