弧矢一(δ CMa / 大犬座δ)是大犬座的一颗恒星，俗名Wezen或Wesen，来自阿拉伯语وزن wazn，意为“重量”。Wazn也是子二（天鸽座β）的名字。

弧矢一是一颗黄-白F型超巨星，视亮度为+1.83星等。它是该星座里的第三亮星，次于天狼星（大犬座α）和弧矢七（大犬座ε）。

Delta Canis Majoris (δ CMa, δ Canis Majoris) is a star in the constellation Canis Major. It has the traditional name Wezen, Wesen, or Wezea. It is a yellow-white F-type supergiant with an apparent magnitude of +1.83. Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified.