Nothing rhymes with silver! Or purple! And there are I think 7 words that don't rhyme.
To the best of my knowledge, there are over 70 words in the English language which do not rhyme with any other words! They are (in alphabetical order):
A - Almond, Angry, Angst, Anxious, Aspirin
B - Bachelor, Breadth, Bulb, Bulbous
C - Calumny, Cannabis, Caveat, Chaos, Chimney, Chocolate, Circus, Citrus, Citizen, Condom
D - Denizen, Depth, Diamond, Different
E - Eighth, Elbow, Else, Empty, Engine
F - Fifth, Film, Foible, Fugue
G - Galaxy, Glimpsed, Golf, Gulf
H - Hostage, Husband
I - Indubitably, Iron
J - Justice
K - ...
L - Laundry, Luggage
M - Monster,
Month, Mulcts
N - Ninth, Neutron, Nostril
O - Obvious, Office, Olive,
OrangeP - Pint, Pedant, Penguin, Pizza, Plankton, Plinth, Promise,
PurpleQ - ...
R - Reptile
S - Sanction, Sandwich, Scalp, Shadow,
SilverT - Transfer, Twelfth
U - ...
V - Vacuum
W - Width, Wolf
X - ...
Y - ...
Z - ...
Wikipedia has even more of them.