I may have too broad or subjective of a definition here, so I will try to end with a more specific definition/example -- but if there is a word similar to the definition listed at the end, that may be the right word even if I am off on the definition.
Perhaps that mess is appropriate for how frustrating it is to verbalize this: is there a word/category for words that are uncannily similar?
The very vague and overly subjective description would be "words that are a little too similar." Googling got me as far as uncanny. It feels like a hard thing to Google, which is admittedly as fitting as it is frustrating.
Example of what a definition might look like if there is an objective term rather than a subjective one: Igneous and Ingenious
- Same number of syllables
- Multiple syllables exhibit similar sounds whether it is a rhyme, off rhyme, assonance, alliteration, etc.
- The words share a high number of letters in a similar or identical order
- (This probably goes too specific to be useful enough to exist) The words could syntactially be said together, but are very unlikely to make semantic sense
Sample sentence: I am literally looking for a word to classify other words, so the best I can do here is "igneous" and "ingenious" for a sample pair.
Thesaurus: uncanny is as good as I could do
Why it doesn't work: I'm trying to figure out if there is a specific word to classify sets of words
Criteria: similarity in function to the word oxymoron, but for words that bear a striking or uncanny similarity.
Whether a compound word or phrase would be acceptable: yes. But a single word would be a much more fun answer, don't you think?