Opaque is used in two senses:
- Grammatical opacity, which has to do with scope.
- Lexical opacity, meaning "you can't reliably analyze the parts of a compound".
Grammatical structures are called opaque when they block inner quantifiers from moving up to the front of the outer clause like normal.
For example, object-incorporating verbs like po are said to be opaque. Quantifications in phrases like po tu poq are restricted to a ficticious small "po + object clause", rather than the encompassing clause.
Another way to think about this is that the tu doesn't leave the definition of the new verb created by po tu X.
Thus po tu pỏq always means "[∀P: poq(P)] ___ is P's", or in English: "___ is everyone's".
And thus po tu pỏq sa kủa means "some rooms are everyone's", regardless of the other quantifiers in the sentence, and not something like "∀[P: poq(P)] ∃[K: kua(K)] K is P's."
In some loglangs, compound words are "transparent", meaning you can analyze their parts. For example, in Loglan, trigru is necessarily a compound of tri (tree) + gru (group). A listener who doesn't know this word can still deduce that it refers to tree-groups in some sense. (The word means "forest".)
Toaq does not have this property: its compounds are opaque. This means that even though muaome is etymologically formed as muao plus me (which may be a useful mnemonic), there is no way to infer the meaning or structure of an unfamiliar word in general, or to even tell that it is a compound.
This gives wordsmiths much more freedom: we can freely make new multi-syllable roots, or "exocentric compounds" like tıqshoaı (which is not a kind of shoaı).