The correct spelling of the word is "equilibrant," which is supported by sources like Wiktionary. Google search results show a significant preference for "equilibrant" with 177,000 hits compared to 2,400 for "equilibriant." This indicates that "equilibrant" is the more widely accepted term. The confusion may arise from varying usage, but the consensus leans towards "equilibrant" as the standard spelling. Overall, "equilibrant" is the preferred and correct form.