functional vs operable

functional

adj
  • Only for functional purposes, notably in architecture 

  • Having semantics defined purely in terms of mathematical functions, without side-effects. 

  • Useful; serving a purpose, fulfilling a function 

  • Of a disease, such that its symptoms cannot be referred to any appreciable lesion or change of structure; opposed to organic disease, in which the organ itself is affected. 

  • In good working order. 

noun
  • A function that takes a function as its argument; More precisely: A function whose argument varies in a space of (real or complex valued) functions and whose value belongs to a monodimensional space. An example is the definite integration of integrable real functions in a real interval. 

  • A scalar-valued linear function on a vector space. 

  • An object encapsulating a function pointer (or equivalent). 

operable

adj
  • Able to be operated or used 

  • Able to be put into operation; practicable 

  • Able to be treated by surgery 

How often have the words functional and operable occurred in a corpus of books? (source: Google Ngram Viewer )