One Word Substitution

Equestrian means 'one who rides on horseback' (from Latin 'equus' = horse). Pedestrian walks, Cosmopolite is worldly, and Spectator watches - none relate specifically to horse riding.

Garrison means 'soldiers in a fortress' stationed for defense. Rabble is a disorderly crowd, Force is general military power, and Swordsman is one skilled with swords - none specifically mean soldiers stationed in a fortress.

Regicide means 'the murder of a king' (from Latin 'rex' = king, 'cidium' = killing). Parricide is killing a parent, Matricide is killing a mother, and Fratricide is killing a brother - the suffix '-cide' means killing, but the prefix must specify the victim.

Brittle correctly describes something that is hard but breaks easily. Crisp means fresh/firm, fragile means easily broken (without the hard aspect), and vulnerable means exposed to harm.

Gregarious correctly describes animals that live in groups/flocks. Nomadic means wandering, pastoral relates to shepherding, and barbarous means uncivilized.

Honorary correctly describes a position held without salary. Gratis means free (but can apply to things), ad hoc means for a specific purpose.

Indispensable correctly means something that cannot be done without. Inaccessible means unreachable, indelible means cannot be erased, and incorrigible means cannot be corrected.

Mercenary correctly describes someone motivated primarily by money. Loquacious means talkative, honorary means unpaid, and equestrian relates to horse riding.

Oligarchy correctly means government by a few powerful people. Anarchy is absence of government, aristocracy is government by the elite, and monopoly is market control by one entity.

Omnipresent correctly means present everywhere simultaneously. Omniscient means all-knowing, omnipotent means all-powerful, and omnivorous means eating all food types.

Fratricide correctly means killing one's brother. Regicide is killing a king, matricide is killing one's mother, and parricide is killing a parent or close relative.

Panacea correctly means a remedy for all diseases or problems. Penchant means a strong liking, and cure is too general.

Omnivorous correctly describes an organism that eats both plants and animals - anything and everything. Herbivorous eats only plants, carnivorous only meat, and cannibalistic eats one's own species.

Irrevocable correctly means something that cannot be changed or recalled once done. Irreparable means cannot be fixed, irritable means easily annoyed, and insatiable means cannot be satisfied.

Verbatim correctly means word-for-word, using exact words. Verbose means using too many words, linguist is a language expert, and plagiarism is stealing someone's work.