underlying, unnoticeable, inobtrusive, inconspicuous, subdued, inward, discreet, see, subliminal, invisible, unconspicuous, hidden, subtle, obscure, restrained, tasteful, retiring, I/you/she etc. would never guess, quiet, undetected, unclear
humble (part of speech: adjective)
modest (part of speech: adjective)
- Neither was Boase altogether happy about the path in life of his spiritual son, although that path seemed to lead, in its unobtrusive manner, upward. - "Secret Bread", F. Tennyson Jesse.
- True religion is quiet, unobtrusive, seeking the shade- its ever- befitting attitude at the feet of Jesus, looking to Him as all in all. - "Memories of Bethany", John Ross Macduff.
- They are good workers, these little brown and yellow men, and unobtrusive and skilled. - "The Killer", Stewart Edward White.