Where does “grown-ass” come from?

grown-ass (English) comes from English ass, from Middle English asse, from Old English assa, from Old English assen, from Latin asinus, from Latin acinus, from Latin acies, from Proto-Indo-European h₂eḱ- — sharp.

grown-ass (English): Grown-up; adult; often used in reproach of an adult's immaturity, or, conversely, in assertion of maturity

Definitions

  1. Grown-up; adult; often used in reproach of an adult's immaturity, or, conversely, in assertion of maturity

Ancestry of “grown-ass”, step by step

grown-ass traces back through two separate lines of ancestry.

via English ass

StepLanguageWordMeaning
1EnglishassAny of several species of horse-like animals,...
2Middle EnglishasseAlternative form of axen
3Old Englishassaass, donkey
4Old Englishassenshe-ass
5Latinasinusa donkey, an ass; an ass, an idiot, a dolt, a...
6Latinacinusa berry, especially the grape; the seed of a...
7Latinaciessharp edge or point; battle line; battle,...
8Proto-Indo-Europeanh₂eḱ-sharp

via English grown

StepLanguageWordMeaning
1Englishgrownpast participle of grow; Covered by growth;...
2Middle EnglishgrowenTo grow usually of plants, fruit, etc
3Old Englishgrōwanto grow, increase, flourish, germinate
4Proto-Germanicgrōanąto green; to grow
5Proto-Indo-Europeanǵʰreh₁-to become green, grow; to grow; to green, to grow
Every word from Proto-Indo-European h₂eḱ-Every word from Latin aciesEvery word from Latin acinus