Longman Dictionary of Contemporary English
Wiktionary
n. (alternative spelling of polo-neck English)
Wikipedia
A polo neck, ' roll-neck' ( UK) or turtleneck ( US, Canada) or skivvy ( Australia, New Zealand) is a garment—usually a shirt—with a close-fitting, round, and high collar that folds over and covers the neck. It can also refer to type of neckline, the style of collar itself, or be used as an adjective ("polo necked").
A simpler variant of the standard polo neck is the mock polo neck (or mock turtleneck), that resembles the polo neck with the soft fold at its top and the way it stands up around the neck, but both ends of the tube forming the collar are sewn to the neckline. This is mainly used to achieve the appearance of a polo neck where the fabric would fray, roll, or otherwise behave badly unless sewn. The mock polo neck clings to the neck smoothly, is easy to manufacture, and works well with a zip closure.
Usage examples of "polo neck".
He wore navy-blue slacks, a polo neck sweater in the same colour and a sports jacket in pale blue tweed by Yves St Laurent.
Rejecting jumper after shirt after skirt, she'd ended up back in the Cadbury-coloured baggy man's polo neck she'd tried on first.