1. Physically toughened
   - tough 
2. Made hard or flexible or resilient especially by heat treatment
   - tempered, treated, hardened

1. Make tough or tougher
   "This experience will toughen her"

See also: callous, calloused, curable, enured, experienced, experient, hardened, inured, rugged, strong, sunbaked, thickened, weather-beaten

Type of: strengthen

• aloof
• aloofly
• aloofness
• alopecia
• alopecia areata
• alopecic
• Alopecurus
• Alopecurus pratensis
• Alopex
• Alopex lagopus
• Alopiidae
• Alopius
• Alopius vulpinus
• Alosa
• Alosa alosa
• Alosa chrysocloris
• Alosa pseudoharengus
• Alosa sapidissima
• Alouatta
• aloud
• alow
• Aloys Senefelder
• alp
• alpaca
• Alpena