case-harden
|case-har-den|
🇺🇸
/ˈkeɪsˌhɑrdən/
🇬🇧
/ˈkeɪsˌhɑːdən/
make the outer layer hard
Etymology
'case-harden' originates from English as a compound of 'case' + 'harden', where 'case' meant 'an outer covering or shell' and 'harden' meant 'to make hard'.
'case' comes from Old French/Anglo-Norman (from Latin 'capsa' meaning 'box, container') and developed senses like 'covering' or 'outer layer'; 'harden' comes from Old English 'heardian' (from 'heard' meaning 'hard'). The compound term 'case-harden' (and the noun 'case-hardening') emerged in industrial metallurgy in the 18th–19th centuries to describe surface-hardening processes.
Initially it literally combined the senses of 'case' (outer layer) and 'harden' (make hard); over time it became a technical term specifically referring to metallurgical surface-hardening processes such as carburizing and nitriding.
Meanings by Part of Speech
Verb 1
to harden the outer surface (the 'case') of a metal object, typically by introducing carbon or nitrogen (e.g., by carburizing, cyaniding, or nitriding) so the surface becomes wear-resistant while the core remains tougher.
To increase wear resistance, engineers case-harden gear teeth.
Synonyms
Antonyms
Last updated: 2025/12/13 10:45