unthinkable, out of the question

Desolated is a door when no guests come knocking. Lit. To hang a net on the door and use it to catch sparrows (as no guests ever come).

practical question (problem)

seldom lending or showing something precious because one values it

Montreal (the largest city in Quebec, Canada) / Montreal (an island in Quebec, Canada, the site of the city of Montreal) / Montreal (a river in Algoma district and Sudbury district, Ontario, Canada)

observatory (place where celestial bodies are observed)

Monrovia (the capital of Liberia)

hydrology

Kyūjitai form of 水文学: hydrology

(phonetics) glottal / guttural- or throaty-sounding speech