A zephyr is a garment worn in competitive rowing.
A zephyr is usually a short-sleeved T-shirt with a front opening, with the opening and sleeve ends trimmed in the colours of the club.
Zephyr, as a garment, appears in the 1927 novel Blind Corner by Dornford Yates. "... I followed immediately, clad only in a zephyr and shorts, and was in the boat almost a soon as he."
References
Zephyr (garment) Wikipedia(Text) CC BY-SA