もっと長く

longer; for longer

→ もっと
phrase Rare #22,051
longer; for longer もっと means “more,” and 長く is the adverbial form of 長い (“long”). Used for duration or length, depending on context.
JA: ここにもっと長くいたい。
EN: I want to stay here longer.

ここにもっと長くいたい

I want to stay here longer.

もっと長く楽しむんなら慌てないでどうやれば..

If you want to enjoy it for longer, how can you do that without rushing…?

— ANORA アノーラ (2024)

次の時はもっと長くいるって約束するよ

I promise I'll stay longer next time.