Where does “sick-ass” come from?

sick-ass (English) comes from English sick, from English sic, from English seek, from Middle English seke, from Old English sēċan, from Proto-West Germanic sōkijan, from Proto-Germanic sōkijaną, from Proto-Indo-European séh₂gyeti — to seek out.

sick-ass (English): Mentally disturbed or unsound; malevolently crazy

Definitions

  1. Mentally disturbed or unsound; malevolently crazy

Ancestry of “sick-ass”, step by step

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

via English sick

StepLanguageWordMeaning
1EnglishsickIn poor health; ill; Having an urge to vomit;...
2EnglishsicThus; thus written; To mark with a bracketed sic;...
3EnglishseekTo try to find; to look for; to search for; To...
4Middle EnglishsekeAlternative form of seken
5Old Englishsēċanto seek or inquire about
6Proto-West Germanicsōkijanto seek, to look for
7Proto-Germanicsōkijanąto seek, look for
8Proto-Indo-Europeanséh₂gyetito give a sign
9Proto-Indo-Europeanseh₂g-to seek out

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
Every word from Proto-Indo-European seh₂g-Every word from Proto-Indo-European séh₂gyetiEvery word from Proto-Germanic sōkijaną