百日の説法屁一つ: “a hundred days of sermonizing, one fart” → a metaphor for how extreme effort something that one has put great effort into can come to nothing after even a slight mistake, much as a hundred days of serious spiritual study can be lost to the winds

火の鳥: A phoenix, more specifically as in Western mythology.

記念碑: monument

比重: specific gravity; relative importance

悲寥:

比量: / 肥料: fertiliser; manure / 飛竜: flying dragon / 匙量: / 悲涼: / 悲寥: / 費了:

比量: / 費了:

標準語: the standard language (of a country); standard Japanese

百科全書: encyclopedia

皇妃: an empress / 口碑: a legend / 工費: construction costs / 公比: a common ratio; a geometric ratio / 公妃: a duchess / 公費: public expenditure / 叩扉: beating on a door; a visit to someone