The words concomitance, concomitants sound the same but have different meanings and spellings. Why do concomitance, concomitants sound the same even though they are completely different words?
The answer is simple: concomitance, concomitants are homophones of the English language.
Occurrence or existence together or in connection with one another.
A concomitant.
The state of being concomitant; a being together or in connection with another.
In <em>Roman Catholic theology</em>, the coexistence of the body and blood of Christ in the single eucharistic element of bread, so that those who partake of the consecrated host receive him in full. Also <internalXref urlencoded="concomitation">concomitation</internalXref>.
Plural form of <xref>concomitant</xref>.
Definitions from The American Heritage® Dictionary of the English Language, 5th Edition., from The Century Dictionary., from Wiktionary, Creative Commons Attribution/Share-Alike License. and Wordnik.
Homophones (literally "same sound") are usually defined as words that share the same pronunciation, regardless of how they are spelled.
If they are spelled the same then they are also homographs (and homonyms); if they are spelled differently then they are also heterographs (literally "different writing").