cardigan
A sweater with no collar.
Nobody. Shakespeare never used the word "sweater".
An 'open neck' or a 'V neck'.
There are many stores that sell collarless shirts. This would depend what brands you like. Once you find the brand you like, then it would be easy to find the collarless shirts.
Kurta
Peter Shaffer
Collarless shirts are worn at various occasions but mostly around the spring and summer seasons. This is also considered as a persons preference and opinion.
pullover
Tom Goes to the Mayor - 2004 White Collarless 2-4 was released on: USA: 26 June 2006
Lana Turner
Sweater is usually spelled "sweat" in French, after the English name. This is a masculine noun pronounced like "sweet".