One word substitute is Deponent.

Deponent: a person who makes a deposition or affidavit under oath.
Appellant: a person who applies to a higher court for a reversal of decision of a lower court.
Witness: a person who sees an event, typically a crime or accident, take place.
Litigant: a person involved in a lawsuit.

One word substitute is Obliterate.

Cancel: decide or announce that (a planned event) will not take place.
Negate: make ineffective; nullify.
Obliterate: destroy utterly; wipe out.
Nullify: make legally null and void; invalidate.

One word substitute is Altruism.

Cynicism: an inclination to believe that people are motivated purely by self-interest; scepticism.
Nepotism: practice among those with power or influence of favouring relatives or friends, especially by giving m jobs.
Philanthropy: desire to promote welfare of ors, expressed especially by generous donation of money to good causes.
Altruism: disinterested and selfless concern for well-being of ors.

One word substitute is Hymn.

Lyric: (of poetry) expressing writer's emotions, usually briefly and in stanzas or recognized forms.
Ode: a lyric poem, typically one in form of an address to a particular subject, written in varied or irregular metre.
Hymn: a religious song or poem of praise to God or a god.
Ballad: a poem or song narrating a story in short stanzas. Traditional ballads are typically of unknown authorship, having been passed on orally from one generation to next.

One word substitute is Philanthropist.

Anthropologist: an expert in or student of anthropology.
Philanthropist: a person who seeks to promote welfare of ors, especially by generous donation of money to good causes.
Seismologist: study of seismic waves, energy waves caused by rock suddenly breaking apart within earth or slipping of tectonic plates.
Optometrist: a person who practises optometry.

One word substitute is Heresy.

Unbelief: lack of religious belief; an absence of faith.
Superstition: excessively credulous belief in and reverence for supernatural.
Non-conformity: principles or practice of Nonconformists, especially Protestant dissent.
Heresy: belief or opinion contrary to orthodox religious (especially Christian) doctrine.

One word substitute is Irritating.

Abhorrent: inspiring disgust and loathing; repugnant.
Irritating: causing annoyance, impatience, or mild anger.
Painful: (of a part of body) affected with pain.
Revolting: causing intense disgust; disgusting.

One word substitute is Convalescence.

Hysteria: exaggerated or uncontrollable emotion or excitement.
Amnesia: a partial or total loss of memory.
Superannuation: regular payment made into a fund by an employee towards a future pension.
Convalescence: time spent recovering from an illness or medical treatment; recuperation.

One word substitute is Kleptomania.

Logomania: pathologically excessive (and often incoherent) talking.
Nymphomania: uncontrollable or excessive sexual desire in a woman.
Kleptomania: a recurrent urge to steal, typically without regard for need or profit.
Hypomania: a mild form of mania, marked by elation and hyperactivity.

One word substitute is Usurer.

Solvent: having assets in excess of liabilities; able to pay one's debts.
Uxorious: having or showing a great or excessive fondness for one's wife.
Usurer: a person who lends money at unreasonably high rates of interest.
Shylock: a ruthless moneylender; a loan shark.