quword
趣词
Word Origins Dictionary
A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
Q
R
S
T
U
V
W
X
Y
Z
radian (n.)
[radian 词源字典]
"angle subtended at the center of a circle by an arc equal in length to the radius," 1879, from
radius
.
[radian etymology, radian origin, 英语词源]
[radian 词源字典]