逆

contrary / opposite / backwards / to go against / to oppose / to betray / to rebel

to walk (side part of split character)

Character component without intrinsic meaning

to rebel / to revolt / a rebel

irreversible

reversible / (math.) invertible

to go against the tide (idiom); to do things all wrong / to try to turn back history / a perverse way of doing things

to hiccup / to belch

belching and retching counterflow (medical term)

irreversible

multiplicative inverse (math.)

traitor

reversibility