Recondite adj. (of a subject or knowledge) Little known, obscure, abstruse. “Recondite information.”

Obsequious adj. Obedient or attentive to an excessive degree. “The obsequious service resulted in an excellent tip.”

Colloquial (ism) adj. (of language) Used in ordinary conversation; not formal or literary. “His lecture was quite engaging due to his colloquial speech.”

Ignoble adj. Not honorable in character or purpose; shameful. “An ignoble act.”

Tenuous adj. Very weak or slight; insubstantial. “A tenuous argument.”

Ostracize v. Exclude (someone) from a society or group. “She felt ostracized by society.”

Irascible adj. Characterized by or arising from anger. (of a person) Easily made angry. “He was always irascible and quick to get into a fight.”

Nescient; Nescience adj. Lacking knowledge; ignorant. “His nescience of the topic was obvious.”

Acrid adj. Having an irritatingly strong and unpleasant taste or smell. Angry and bitter. “An acrid odor filled the room.”

Elucidate v. Make (something) clear; explain. “The presentation will help to elucidate the project.”