WordNet sense 1 (difficult to find):

hidden

WordNet sense 2 (hidden on any grounds for any motive):

concealed

WordNet sense 3 (make less visible or unclear):

becloud, befog, cloud, fog, mist, obnubilate, haze over

WordNet sense 4 (not famous or acclaimed):

unknown, unsung

WordNet sense 5 (not bringing honor and glory):

dishonorable, inglorious

WordNet sense 6 (make unclear, indistinct, or blurred):

blur, confuse

WordNet sense 7 (not drawing attention):

unnoticeable

WordNet sense 8 (not prominent or readily noticeable):

inconspicuous, invisible

WordNet sense 9 (remote and separate physically or socially):

apart, isolated

WordNet sense 10 (not joined or linked together):

unconnected

WordNet sense 11 (marked by difficulty of style or expression):

dark

WordNet sense 12 (difficult to understand):

incomprehensible

WordNet sense 13 (not clearly understood or expressed):

vague

WordNet sense 14 (not clear to the mind):

unclear

WordNet sense 15 (make undecipherable or imperceptible by obscuring or concealing):

hide, obliterate, veil, blot out

WordNet sense 16 (make difficult to perceive by sight):

bedim, benight

WordNet sense 17 (make obscure or unclear):

overcloud