Meaning

adjective concerned with work or important matters rather than play or trivialities

adjective of great consequence

adjective causing fear or anxiety by threatening great harm

originEtymology tree Proto-Indo-European *seh₁- Proto-Indo-European *-rós Proto-Italic *sēros Latin sērus Proto-Indo-European *-yós Proto-Italic *-ios Old Latin -ios Latin -ius ? Proto-Indo-European *swer- Proto-Indo-European *-yós Proto-Italic *swerjos? Latin sērius Proto-Indo-European *h₃ed- Proto-Indo-European *-os Proto-Indo-European *h₃édosder.? Proto-Italic *-ōtsos or *-otsos Latin -ōsus Medieval…

Etymology from Wiktionary, CC BY-SA 3.0