costumier
noun /kɒsˈtjuːmiə(r)/
  /kɑːsˈtuːmieɪ/
 (British English) (North American English costumer)
- a person or company that makes costumes or has costumes to hire, especially for the theatre
- a firm of theatrical costumiers
 
Word Originmid 19th cent.: French, from costumer ‘dress in a costume’, from Italian costume ‘custom, fashion, habit’, from Latin consuetudo, from consuetus, past participle of consuescere ‘accustom’, from con- (expressing intensive force) + suescere ‘become accustomed’.