Dictionary

crew neck en · ADJ

(not-comparable) Referring to the collar of pullover garments and usually of sweaters and T-shirts, when [the collar] circles the neck.
- The designer herself was wearing tailored caramel-coloured trousers with a toning crew neck knit, because “it’s work, and I have too much to do to get dressed up”. 2017 October 2, Jess Cartner-Morle, “Stella McCartney lays waste to disposable fashion in Paris”, in the Guardian:
(not-comparable) Referring to a garment's collar whose front is meant to ride up onto the neck, sometimes to Adam's apple level.

Spelling	Features	Labels	Source
crewneck		alternative	lexicographic

A round neckline with a ribbed texture.
- For a writer celebrated for his control of his characters’ inner lives, for a husband and father notoriously prickly about his expression of the suburban proprieties — the crewneck Shetland sweater and khakis, the plummy faux-Brahmin accent, the adoring Labrador at his feet, the woodpile neatly stacked and grass hand-scythed — here was scandal in full spate, sludge flooding over his family and friends. 2009 March 15, Geoffrey Wolff, “Suburban Suffering”, in New York Times:
(broadly) A shirt, sweater, or similar garment with such a neckline.

Spelling	Features	Labels	Source
crewneck		alternative	lexicographic
crew necks	Number=Plur		lexicographic