transmission, gearbox (mechanical assembly of gears that changes the torque and speed of shaft rotations)

prejudicial treatment, favoritism

to show prejudicial treatment, to display favoritism

(grammar) irregular conjugation / irregularity / (grammar) translative case

a musical arrangement

arrange music

hentaigana: any of the hiragana made obsolete in Meiji-era reforms that enforced having one hiragana for each syllable

bianqing (musical instrument)

admission to a school / annexation, incorporation

admit, transfer to a school / annex, incorporate