The story
- Latinrudis
- Latinrudīmentum
- Old Frenchrudiment
- Englishrudiment
- New Latinrudimentariusder.?
- English todayrudimentary
From rudiment + -ary (adjectival suffix), perhaps after New Latin rudīmentārius, from Classical Latin rudīmentum (“first attempt; beginning”) + -ārius (adjectival suffix). Compare French rudimentaire.
Etymology from Wiktionary, CC BY-SA 4.0.