But rhythm doesn't have an "s" - it's a "th" . . .

I suppose logarithm doesn't count, since it contains the complete homophone. Heh, that's sorta amusing. There is no rhyme for rhythm. Somehow it makes me think of rap.

melancholy

voiced vs. unvoiced sybillant. It's a rhyme, I tell you.

okay, okay, I believe you believe it's a rhyme

Girth

Wayne.

Oh sorry, this isn't word association.

lol

Rhymes with "worth."

Technically, a word rhymes if it has the same vowel sounds in each syllable from the stressed syllable onwards, meaning you only have to rhyme with "-choly". So in that case, "folly" and "trolley" would both work.

The folly of the melancholy trolley.

My word is expatiate.

harangue \huh-RANG\, noun:
1. A speech addressed to a large public assembly.
2. A noisy or pompous speech; a rant.

transitive verb:
1. To deliver a harangue to; to address by a harangue.

intransitive verb:
1. To make a harangue; to declaim.

scrofulous

And another personal favorite ... crenulation

One we had the giggles over in high school - masticate.

crenulation reminds me of one of my favorites:
crepuscular

Quintessences.