adversa

adj. opposite, contrary; adverse, opposed; hostile; perverse

v. oppose, resist, contest

adj. adverse, contrary; opposed, averse; hostile; unfavorable

ADVersae N F
enemy/ ADVersary/opponent (female)

= adverse, untoward, averse.
Ex: An increase in recall tends to have an adverse effect on another measure of performance, precision -- as recall is increased precision is lowered.
Ex: Efforts to destigmatize euthanasia or even encourage it for some groups may have the untoward effect of promoting suicide in other groups.
Ex: The advantage of an acoustic pulse as the averse stimulus is discussed.