the.com/monism

means The philosophical view that reality is fundamentally a single substance or kind of thing, with all apparent divisions being variations within that one underlying unity.

from Coined in the 18th century from Greek 'monos' meaning 'alone' or 'single' — the same root behind 'monologue' and 'monk' (someone who goes it alone) — plus the philosophical suffix '-ism' marking a doctrine. German philosopher Christian Wolff is usually credited with formalizing the term, giving a one-word label to an idea far older than the word itself: thinkers from the ancient Greeks onward had already been arguing that beneath the world's apparent multiplicity lies a single stuff, substance, or principle.