collarless

adjective3

1. •
   Of a garment, having no collar.

   • Their records have sold 2,500,000 copies, and crowds stampede for a chance to touch the hem of the collarless coats sported onstage by all four of them. — 1963
2. •
   Of a dog, not wearing a dog collar.

   • I wandered about Paris like a lost dog, like a collarless dog. — 1963
3. •
   (no longer used) Of a man, not wearing a detachable collar.

   • The driver of the jitney was a young, swarthy prairie man, in shirt sleeves, and collarless, with a derby on one side of his head […] — 1918