The character 等 originally depicted bamboo slips (竹, bamboo, at the top) arranged in equal tiers — suggesting things of the same rank or grade. The meaning extended from "equal/ranked" to "and so on" (等等), and separately to "to wait," likely from the idea of holding in place until things are level or ready. The "to wait" sense is now its most common usage in everyday speech.

等 is extremely versatile in Mandarin. Reduplicated as 等等 (děng děng), it means "et cetera / and so on" — a completely different meaning from the verb. Chinese speakers also use 等一下 (děng yīxià, "wait a moment") constantly in daily life, the equivalent of "hold on" or "just a sec." Don't confuse 等 the verb with its grammatical use as a particle meaning "etc." — context always makes it clear.