Meaning of A Sentence Using 降り止んだ

Question

I came across this phrase:

いつのまに降り止んだ
雨上がり煌めき出す街

And I don't understand the grammar behind the word 降り止んだ.

I've seen two translations for it: "Without anyone noticing, the rain let up. With the rain having stopped, the town sparkles." and "In the meantime, the rain stopped falling and the town started to sparkle".

I'm not sure which is more accurate, though they are quite similar.

My question is this: Regarding 降り止んだ, what is the grammar behind its current conjugation and the ending, "やんだ". Also I've seen it written in romaji as both "oriyanda" and "furiyanda". Which is correct?

ありがとう

Answer 1

Simply, [降り止む]{ふりやむ} is an established compound verb, and you have to memorize it as one word.

ふり‐や・む【降り▽止む】

［動マ五（四）］降っていた雨や雪などがやむ。「雪が―・まない」

降り止む

Godan verb with mu ending, intransitive verb

1. to stop raining or snowing​

According to Compound Verb Lexicon, there are five similar verbs ending with 止む:

• 泣き止む (e.g., 赤ちゃんが泣き止む)
• 鳴り止む (e.g., 雷が鳴り止む)
• 鳴き止む (e.g., 小鳥が鳴き止む)
• 降り止む (e.g., 雨が降り止む, 雪が降り止む)
• 吹き止む (e.g., 風が吹き止む)

Although 鳴き止む may be uncommon, the other four are worth memorizing.