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
undertone (n.)
[undertone 词源字典]
1762, "low or subdued tone," from
under
+
tone
(n.). Figurative sense of "undercurrent of feelings, etc.," is attested from 1861.
[undertone etymology, undertone origin, 英语词源]