The Collaborative International Dictionary
Abacist
Abacist \Ab"a*cist\ ([a^]b"[.a]*s[i^]st), n. [LL abacista, fr. abacus.] One who uses an abacus in casting accounts; a calculator.
Wiktionary
abacist
n. One who uses an abacus#English in casting accounts; a calculator. (First attested from around (1350 to 1470).)(R:SOED5: page=2)
Usage examples of "abacist".
Abacists, who defended the use of the counting table, battled the Algorists, who preferred the new numbers.