Open English Wordnet
Adjectives
(a)unpretentiouslacking pretension or affectation“an unpretentious country church”, “her quiet unpretentious demeanor”
(a)unostentatious, unpretentious, unpretendingnot ostentatious“his unostentatious office”, “unostentatious elegance”
(s)understated, unostentatious, unpretentiousexhibiting restrained good taste“the room is pleasant and understated”