Dictionary.com
definitions

arbiter elegantiae

[ahr-bi-ter ey-le-gahn-tee-ahy; English ahr-bi-ter el-uh-gan-shee-ee]

noun Latin.

a judge of elegance or matters of taste.
Also ar·bi·ter e·le·gan·ti·a·rum [ahr-bi-ter ey-le-gahn-tee-ah-roo m; English ahr-bi-ter el-uh-gan-shee-air-uh m] /ˈɑr bɪˌtɛr ˌeɪ lɛˌgɑn tiˈɑ rʊm; English ˈɑr bɪ tər ˌɛl əˌgæn ʃiˈɛər əm/.

Petronius

[pi-troh-nee-uh s]

noun

Ga·ius [gey-uh s] /ˈgeɪ əs/, Gaius Petronius ArbiterArbiter Elegantiae, died a.d. 66?, Roman satirist.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
British Dictionary definitions for arbiter elegantiae

Petronius

noun

Gaius (ˈɡaɪəs), known as Petronius Arbiter. died 66 ad, Roman satirist, supposed author of the Satyricon, a picaresque account of the licentiousness of contemporary society
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012