plain udon noodles; udon without toppings
Refers to udon served in hot broth without any toppings, as opposed to 掛けうどん which may include toppings. A simple, basic style of udon.
See also: かけうどん
On cold days, I crave plain udon noodles.
Adding tempura bits to plain udon makes it delicious.
Standard spelling for plain udon noodles.
Rarely used kanji form; 饂飩 is an uncommon spelling for うどん.
素 (plain) + うどん (udon noodles). The exact historical derivation is uncertain, but the term straightforwardly describes udon served without additional toppings.