Other hyponyms of letter of the alphabet include
ascender,
descender,
digram,
digraph,
initial,
A,
a,
B,
b,
C,
c,
D,
d,
E,
e,
F,
f,
G,
g,
H,
h,
I,
i,
J,
j,
K,
k,
L,
l,
M,
m,
N,
n,
O,
o,
P,
p,
Q,
q,
R,
r,
S,
s,
T,
t,
U,
u,
V,
v,
double-u,
W,
w,
ex,
X,
x,
wye,
Y,
y,
ezed,
izzard,
Z,
z,
zed,
zee,
alpha,
beta,
gamma,
delta,
epsilon,
zeta,
eta,
theta,
iota,
kappa,
lambda,
mu,
nu,
xi,
omicron,
pi,
rho,
sigma,
tau,
upsilon,
phi,
chi,
khi,
psi,
omega,
aleph,
beth,
gimel,
daleth,
he,
waw,
zayin,
heth,
teth,
yodh,
kaph,
lamedh,
mem,
nun,
samekh,
ayin,
pe,
sadhe,
qoph,
resh,
sin,
shin,
taw,
polyphone,
block capital,
block letter,
vowel,
consonant,
yus.