One Word Substitution

'Irritable' means easily irritated or annoyed.

'Herbivorous' refers to plant-eating animals. 'Aquatic' is the correct word here. 'Carnivorous' refers to flesh-eating animals. 'Heterotroph' is an organism that feeds on organic substances.

Hermitage refers to any secluded place of residence or habitation.

Devour means to eat something quickly and greedily. It conveys the sense of consuming food ravenously or voraciously, which matches the given phrase perfectly. The other options relate to dedication or pleasure but not specifically to eating.

Truism: A statement that is obviously true and the truth is well known.

Censorious means having or showing a tendency to criticize someone or something severely. It describes a person who is habitually critical and finds fault with others, which is exactly what the question asks for.

A spokesman is someone who speaks on behalf of others or represents a group in public communications. This directly matches the definition 'one who speaks for others'. Commentators and announcers speak about things, not for others.

A novice is someone who is new to a job, field, or activity - a beginner or learner. This is the exact opposite of seasoned or veteran, which are listed as distractors. The word precisely captures the meaning of being new in a role.

The word insoluble describes something that cannot be solved, dissolved, or resolved. Memorable means worth remembering, vandalism refers to deliberate damage to property, and perpetual means lasting forever. Thus, insoluble is the correct single-word substitute.

Colleagues are people who work together in the same profession or workplace. This directly matches the definition 'people working together in the same office'. 'Contingent' refers to a group representing something, while 'relative' means family member.

Remote means far away in distance or time, which directly matches the meaning of a distant place. Obsolete refers to something outdated, while Patricide specifically means killing one's father.

Glutton specifically means a person who eats excessively or is fond of eating too much. Bellicose refers to warlike behavior, while Irrelevant means not connected to the matter at hand.

Egoist refers to someone who is self-centered and primarily thinks or talks about themselves. Husband and Bachelor are marital status terms, not personality traits.

Celibacy refers to the state of being unmarried or abstaining from marriage and sexual relations. Monogamy means having one spouse, while Chaste means pure or morally pure.