Some words are notoriously difficult to find a true rhyme for, such as orange, purple, and silver. But there is hope yet …
Blorange, or The Blorange, is a hill in Wales.
QI : What Rhymes With Orange?
However, according to Alan Skorkin, this is not strictly correct as he alleges that the correct pronunciation of Blorange is “Blorins”.
Skorkin notes that there are two other words that rhyme with orange:
“Gorringe”: A family name which, if pronounced in a particular way, rhymes with orange.
“Sporange“: A a plant that produces spores. This one is also arguable since, technically speaking, it should be sporangium rather than sporange since sporangia is the plural form of the word.
However, an article on Oxford Dictionaries Online, “Are there any words that rhyme with orange?“, says that sporange is “a very rare alternative form of sporangium (a botanical term for a part of a fern or similar plant)”.
If “sporange” is accepted by the Oxford Dictionary, then that is a pretty good endorsement for its usage.
QI : What rhymes with purple?
“Burple” was the name of a now discontinued drink mix that was made in California.
There is an entry for “hirple” in A Glossary of North Country Words, In Use : With Their Etymology, and Affinity to Other Languages (1829, page 155):
“HIRPLE, or HIPPLE, to halt, to walk lame, to creep. V. Jam. hirple; and Crav. Gloss, herple.”
The word “chilver” (a female lamb) rhymes with “silver”.