Full name:
RCA Thesaurus,
or as was customary during the 1950s:
R.C.A. Thesaurus

Succeeded by the RCA New Thesaurus label New Thesaurus in the early 1960s.

It should not be confused with the NBC Transcription service: . The ultimate owner of both where the same during the 1930s and onwards. However, their operations were separated into two divisions of RCA.

The RCA Thesaurus has its origin in the RCA-Victor division, and remained there until 1968 as the RCA New Thesaurus..
The NBC Transcription service grew out of the NBC radio network industrial activities. They operated separate catalogues until c. 1943-44, when the NBC Orthacoustic (ortho-acoustics = proper or right acoustics) transcription seems to end. (but see also NBC produced The National Guard-transcriptions, )