Meanings:

• Heaven or heavens
• Sky
• Compass

Masculine noun. The word is dual in form (ending in -ַיִם) which normally indicates two things (like eyes and hands), however, however it functions as a plural. Deuteronomy 10:14plugin-autotooltip__default plugin-autotooltip_bigDeuteronomy 10:14

Hebrew הֵ֚ן לַיהוָ֣ה אֱלֹהֶ֔יךָ הַשָּׁמַ֖יִם וּשְׁמֵ֣י הַשָּׁמָ֑יִם הָאָ֖רֶץ וְכָל אֲשֶׁר בָּֽהּ ESV Behold, to the LORD your God belong heaven and the heaven of heavens, the earth with all that is in it. NIV To the LORD your God belong the heavens, even the highest heavens, the earth and everything in it. ἰδοὺκυρίουτοῦθεοῦσουὁοὐρανὸςκαὶὁοὐρανὸςτοῦοὐρανοῦἡγῆκαὶπάνταὅσαἐστὶνἐναὐτῇ… states that “heaven and the heavens of heavens” belong to God implying layers or realms of heaven.

This word refers to everything above the earth, from the visible sky to the unseen dwelling place of God. Its meaning is context dependent, for example

• The visible sky where birds fly and the clouds move, e.g. Genesis 1:20plugin-autotooltip__default plugin-autotooltip_bigGenesis 1:20
  
  Hebrew וַיֹּ֣אמֶר אֱלֹהִ֔ים יִשְׁרְצ֣וּ הַמַּ֔יִם שֶׁ֖רֶץ נֶ֣פֶשׁ חַיָּ֑ה וְעוֹף֙ יְעוֹפֵ֣ף עַל הָאָ֔רֶץ עַל פְּנֵ֖י רְקִ֥יעַ הַשָּׁמָֽיִם ESV And God said, “Let the waters swarm with swarms of living creatures, and let birds fly above the earth across the expanse of the heavens.” NIV And God said, “Let the water teem with living creatures, and let birds fly above the earth across the expanse of the sky. καὶὁθεόςἐξαγαγέτωτὰὕδαταἑρπετὰψυχῶνζωσῶνκαὶπετεινὰπετόμεναἐπὶτῆςγῆςκατὰτὸστε…
• Space or the celestial realm where the sun, moon and stars are placed, e.g. Genesis 1:14-17
• The divine realm where God and his angels dwell, e.g. Psalm 115:3plugin-autotooltip__default plugin-autotooltip_bigPsalm 115:3
  
  Hebrew וֵֽאלֹהֵ֥ינוּ בַשָּׁמָ֑יִם כֹּ֭ל אֲשֶׁר חָפֵ֣ץ עָשָֽׂה ESV Our God is in the heavens; he does all that he pleases. NIV Our God is in heaven; he does whatever pleases him. NLT Our God is in the heavens, and he does as he wishes. LXX ὁ δὲ θεὸς ἡμῶν ἐν τῷ οὐρανῷ ἄνω ἐν τοῖς οὐρανοῖς καὶ ἐν τῇ γῇ πάντα ὅσα ἠθέλησενἐποίησεν

The word is often paired with the “earth” (אֶרֶץ) to mean “everything”