(mathematics) quod erat demonstrandum (that which was to be proved)

(Internet slang) a dead fad; out of fashion; no longer trendy

card reader

three, 3 / third

the third day of the month / three days

(colloquial) current boyfriend

(slang) Alternative form of 彼氏 (kareshi, “boyfriend”)

everyone, one and all

zero on a test etc., no points earned / freezing point / zero (value of a function’s independent variables when the value of the function is zero)

to turn on, to switch on