From atsam; power; hence, body -- might, strong, substance.
see HEBREW atsam
H6108. otsem
עֹ֫צֶם noun [masculine] might, bones; —
1 might, construct ׳י יָדִי Deuteronomy 8:17, ׳י יָָֽדְךָ Job 30:21; suffixעָצְמָהֿ Nahum 3:9 (Ges§ 93e); + ׳בְּי רוּחז Isaiah 11:15 (Thes and others; for ר ׳בַּעְיָם ᵑ0).
2 bones (collective): suffix עָצְמִי Psalm 139:15 = my frame.