From The Free On-line Dictionary of Computing (19 January 2023):
FLIP
1. An early assembly language on the G-15.
[Listed in CACM 2(5):16 (May 1959)].
2. ["FLIP User's Manual", G. Kahn, TR 5, INRIA 1981].
3. Formal LIst Processor.
An early language for pattern-matching on Lisp structures,
similar to CONVERT.
["FLIP, A Format List Processor", W. Teitelman, Memo
MAC-M-263, MIT 1966].
(1995-01-31)