外線

(military) line of troops encircling an enemy position / (telephony) outside line / (basketball) outside the three-point line

outside / in addition / foreign / external

thread / string / wire / line / CL:條|条[tiao2],股[gu3],根[gen1] / (after a number) tier (unofficial ranking of a Chinese city)

infrared ray

ultraviolet ray

ultraviolet light

infrared guided missile