We explore the semantics and typology of functional morphemes encoding *apprehensional*, i.e. negative prospective, meanings through a detailed case study of the adjunct uses of the apprehensional morpheme *=sa'ne* APPR in A'ingae (or Cofán, ISO 639-3: con, an Amazonian isolate). We provide the first formal semantic account of apprehensional morphemes. In a structure [*p* [*q=sa'ne*]], *=sa'ne* APPR encodes a modal semantics where the goal worlds of the actor responsible for *p* avoid a salient situation *r*. In the *avertive* use, the agent strives to avoid *q*: *r* ⇔ *q*. In the *in-case* use, the agent strives to avoid *r*, the negative extension of *q*: *r* ⇒ q and *q* !⇒ *r*. In the *timitive* use, the agent strives to avoid a salient situation involving the entity *q*. Our formalization captures our core insight into apprehensional adjunct semantics: all three uses of *=sa'ne* APPR are in a sense *avertive*, differing in what situation is to be averted. By revealing inherent asymmetries among apprehensional functions, our account makes two substantial predictions with regards to typological patterns in apprehensional morphology. *Precautioning asymmetry* predicts non-existence of morphemes with in-case but no avertive uses. *Timitive asymmetry* predicts non-existence of morphemes with avertive and timitive but no in-case uses. While the available published data is scant, it supports both predictions.