deformed bar; deformed round bar
Technical term in construction and civil engineering for a round steel bar with surface deformations to improve bonding with concrete.
Deformed round bars are often used in reinforced concrete.
異形鉄筋 is the broader term for deformed reinforcing bars, while 異形丸鋼 specifically refers to round deformed bars.
Compound of 異形 (deformed, irregular shape), 丸 (round), and 鋼 (steel). The term directly describes the product: a round steel bar with surface deformations.