In the Pilot/Controller Glossary, this is the definition of "Chaff" and would be its meaning in the context of "Additional Services" referenced in your question.
CHAFF- Thin, narrow metallic reflectors of various lengths and
frequency responses, used to reflect radar energy. These reflectors,
when dropped from aircraft and allowed to ...
This is a partial answer (allowed) that I'm making a community wiki.
Source: Google Ngram Viewer
The usage above shows that the term base leg came after traffic pattern, which was confirmed in a Flying Magazine issue (Jun 1948, p. 64):
That linked issue shows that the base leg was also known as the crosswind leg (which today is the leg after the first turn ...