Not ostentatious:
— His unostentatious office.
— Unostentatious elegance.

synonyms: unpretending, unpretentious.

Roget 881: modest, diffident; humble etc. 879; timid, timorous, bashful; shy, nervous, skittish, coy, sheepish, shamefaced, blushing, overmodest.    unpretending^†, unpretentious; unobtrusive, unassuming, unostentatious, unboastful^†, unaspiring; poor in spirit.    out of countenance etc. (humbled) 879.    reserved, constrained, demure.    ... show more

Polish: bezpretensjonalny

Exhibiting restrained good taste.

synonyms: understated, unpretentious.