What to use in polite company: Speedup or Scalability?

This just burns my biscuits! (No, I'm not sitting on a red hot stove like Yosemite Sam.) I can let some things go by without comment. Interchanging "concurrent" and "parallel" is a minor offense, for example. However, confusing the differences between "speedup" and "scalability" gets me smelling smoke. As a card-carrying Vocabunista (Noah Webster Chapter), I must set the record straight and urge each and everyone of you reading this to use the proper word for the proper concept.

Scalability is a (comparative) quality of an application and its execution profile in the face of changing resources (both more and less). There is no unit of measure for scalability, much like there is no unit of measure for greenness (a leaf is more green than a twig). Speedup is the ratio of serial execution time to parallel execution time (for a given number of threads/processes and cores). It is a dimensionless number and usually expressed as a percentage or a multiplier (e.g., 2X). (Other examples of dimensionless numbers include albedo, Reynolds number, drag coefficient, and Weaver flame speed number.) 

An application is considered to be more scalable the longer (or closer) it can maintain a fixed relationship with linear speedup as the number of cores and threads increases.  We can say App_A is more scalable than App_B if App_A has higher speedup beyond some number of cores/threads.  But, we don't say App_A has 2.8 fleginites more scalability than App_B.

As you read through some of the papers and articles collected in the Intel Software Network, you may find the term "scalability" used in place of "speedup." I can only think that the reason for this is becasue the former term is sexier than the former. (Even so, I'm sure Ricardo Montalban would use them correctly, if he ever has occasion to do so.) Please, let me apologize in advance for this word misuse. I'm trying to educate my colleagues here at Intel and abroad. Won't you help by using the proper term in the proper context? My biscuits thank you.
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