円えん周しゅう

え

ん

しゅ

う

Common wordJLPTN2Freq.FrequencyTop 50,000

Meanings

1

noun, noun which may take the genitive case particle 'no'

Refers to the distance around a circle. Often used in mathematical contexts.

直ちょっ径けい
直径 means 'diameter', the straight line through the center of a circle, while 円周 is the distance around the circle.
半はん径けい
半径 means 'radius', half the diameter, whereas 円周 is the full perimeter length.

Compound of 円 (circle) and 周 (circumference, perimeter). The reading is on'yomi.