An undefined coined term for an element – i.e., an undefined “nonce word”-defined  element – may trigger a “means plus function” interpretation of  that element.
To be sure, the case law does not sufficiently distinguish between a “nonce word” and a defined “nonce word”, a point yet to be fully appreciated.  The law relating to a “nonce word”-defined element is explained in detail in the writer’s monograph[FN*]  (excerpt attached).

FirstToFilePatentDraftingMar28NONCE

Regards,
Hal

[FN*] FIRST TO FILE PATENT DRAFTING, § 18[b][6], “Nonce” Definition to Trigger “Means” § 112(f)  Definition (pp. 395-400)(2016)(excerpt attached).