The Hebrew word for sunset is הַשְּׁקִיעָה , literally, the setting. In Rabbinic literature, sunset is termed שְׁקִיעַת הַחַמַּה, the setting of the sun, where החמהrefers to the sun (literally, that which is hot).
שקיעה is the noun form of the active-simple פָּעַל verb לִשְׁקוֹעַ, meaning to sink or to settle in a low place.
As for an example of השקיעה in context, I’ll quote from Danny Sanderson’s beloved song:
הַבִּיטִי לַשְּׁקִיעָה, עֲדַיִן לֹא עָבַר זְמַנָּהּ. Look at the sunset. It’s not over yet (literally, its time has not yet passed). And as for sunrise, well, here’s an earlier entry.
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