the sky

something empty / ineffectual / false

by heart, from memory, by rote

empty; vain; sky

(genetics) mutation

carpet bombing

a machine, a device; a contraption / a loom / an opportunity, a chance to do something; the right time or moment / something of great importance: the linchpin of the matter

indicates aircraft / indicates paper aeroplanes / indicates lives in video games

indicates machines / indicates airplanes

a trap or snare that works by beheading the bird or beast caught in it