an arrangement of five objects, as trees, in a square or rectangle, one at each corner and one in the middle.
a gadget; dingus; thingumbob.
a screen or mat covered with a dark material for shielding a camera lens from excess light or glare.
an arrangement of five objects, as trees, in a square or rectangle, one at each corner and one in the middle.
a printed punctuation mark (‽), available only in some typefaces, designed to combine the question mark (?) and the exclamation point (!), indicating a mixture of query and interjection, as after a rhetorical question.
1590s, "one who performs mechanical or surgical operations," agent noun from operate (q.v.). Meaning "one who carries on business shrewdly" is from 1828. Specific sense of "one who works a telephone switchboard" (1884) grew out of earlier meaning "one who works a telegraph" (1847).
Mathematics A function, especially one from a set to itself, such as differentiation of a differentiable function or rotation of a vector. In quantum mechanics, measurable quantities of a physical system, such as position and momentum, are related to unique operators applied to the wave equation describing the system.
A logical operator.
Genetics A segment of chromosomal DNA that regulates the activity of the structural genes of an operon by interacting with a specific repressor.