This insistence on terminology is sadly incorrect, and should be: multitasking isn't parallel processing.
Concurrency and parallelism are very general, vague terms that mean approximately the same thing: processing of some unspecified kind happening simultaneously.
For instance, parallelism can be in a single thread: "instruction-level parallelism" (pipelines in a CPU: fetching some instructions while others are being decoded and others still are executing on multiple functional units).
Concurrency and parallelism are very general, vague terms that mean approximately the same thing: processing of some unspecified kind happening simultaneously.