等差

degree of disparity / equal difference

class / rank / grade / equal to / same as / to wait for / to await / et cetera / and so on / et al. (and other authors) / after / as soon as / once

difference; discrepancy / (math.) difference (amount remaining after a subtraction) / (literary) a little; somewhat; slightly

different / wrong; mistaken / to fall short; to lack / not up to standard; inferior / Taiwan pr. [cha1]

to send (on an errand) / (archaic) person sent on such an errand / job; official post

used in 參差|参差[cen1 ci1]

arithmetic progression

arithmetic series (such as 2+4+6+8+...)