One Word Substitution

Antique means existing since old times or dating from an earlier period. Animate means alive, edible means edible, and feminist relates to women's rights - none fit the meaning.

Insolvent specifically means unable to pay debts. Panacea is a cure-all, invincible means unbeatable, and sinecure is a paid position with little work.

 One who believes everyone is credulous.

Monarchy is government by a king, queen, or monarch. Autocracy is rule by one person (not necessarily royalty), oligarchy is rule by a small group.

Inexplicable means something that cannot be explained or accounted for. Improbable means unlikely, inimitable means unique/unequalled, and doesn't fit.

Inaudible means unable to be heard. Booming means loud, insolvent means unable to pay debts.

Homicide is the killing of one person by another. Regicide is killing a king, patricide is killing one's father, and fratricide is killing one's brother.

Voluntarily means of one's own free will or by choice. Obligatory means required, essential means necessary.

Polyandry refers to the practice of a woman having multiple husbands simultaneously. Polygamy is a broader term that can mean multiple spouses of either gender, while monogamy means having only one spouse. The key distinction is that polyandry specifically involves one wife with multiple husbands.

Monogamy is the practice of being married to only one person at a time. Bigamy is marrying a second person while still legally married to the first (illegal in most jurisdictions). The question asks for marrying only one person, making monogamy the correct answer.

 One someone takes a side, he or she is partial to that side. Hence, 'taking sides' is partiality.

An antiseptic is a substance that prevents or stops the growth of microorganisms that cause putrefaction (decay/rotting). Antiseptics are used to clean wounds and prevent infection. Eligible means qualified, egoist refers to self-centered behavior, and fatalist believes in destiny.

 When there is no rain, it is a drought.

A pessimist is someone who habitually sees the negative or worst aspects of things - they 'look at the dark side'. An optimist is the opposite, seeing the positive side. Illegible refers to handwriting that cannot be read.

 Someone worth to be chosen for someting is eligible for that.

An eccentric person is someone with unconventional or unusual habits, behavior, or opinions that deviate from the norm. Genius refers to exceptional intellectual ability, while germicide kills germs. Eccentricity is about being uniquely different from societal norms.

A biped is an animal that walks on two feet. 'Bi-' means two, and '-ped' relates to feet. Humans are bipeds. A duet is a musical performance by two people, and novice means beginner. Biped specifically refers to two-footed locomotion.

To instigate means to urge, provoke, or incite someone to do something - often something negative or wrongful. Instigate can mean encouraging someone toward evil or harmful actions. Help is the opposite, and expiate means to make amends for sin.

Deterioration is the process of becoming progressively worse - going from bad to worse. It describes decline in quality, condition, or strength. Brittle means easily broken, eradicate means to eliminate completely, and blonde is a hair color.

A germicide is a substance that destroys germs or microorganisms. 'Germi-' refers to germs, and '-cide' means killing. Fatalist believes in destiny, drought is lack of rain, so germicide is the correct answer for something that destroys germs.

A spendthrift is someone who spends money wastefully or excessively - the opposite of miser. Cruel means causing pain, miser means hoarding wealth, so spendthrift is the correct term for someone who spends too much.

Matchless means having no equal or peer - something that has no match. It describes something unparalleled or incomparable. Original means first or primary, and epitaphic relates to tombstone inscriptions.

Irreparable describes something that cannot be repaired or fixed - damage beyond correction. 'Ir-' means not, 'reparable' means able to be repaired. Difficult and complex describe challenges but not impossibility of repair.

An aviary is a large cage, house, or enclosure for keeping birds. A parasol is a sunshade, a zoo houses various animals, making 'aviary' the specific term for a bird enclosure.

A parasol is a lightweight umbrella used as a sunshade, traditionally carried by ladies. Canopy refers to a covering, bumbershoot is informal for umbrella, but parasol specifically denotes a lady's sun umbrella.