Verbs

(v)obscure, befog, becloud, obnubilate, haze over, fog, cloud, mistmake less visible or unclear“The stars are obscured by the clouds”, “the big elm tree obscures our view of the valley”
(v)confuse, blur, obscure, obnubilatemake unclear, indistinct, or blurred“Her remarks confused the debate”, “Their words obnubilate their intentions”
(v)obscure, bedim, overcloudmake unintelligible or unclear“The distinction was obscured”
(v)obscurereduce a vowel to a neutral one, such as a schwa
(v)obscure, blot out, obliterate, veil, hidemake undecipherable or imperceptible by obscuring or concealing“a hidden message”, “a veiled threat”

Adjectives

(s)obscure, vaguenot clearly expressed or understood“an obscure turn of phrase”, “an impulse to go off and fight certain obscure battles of his own spirit” (Anatole Broyard), “their descriptions of human behavior become vague, dull, and unclear” (P.A.Sorokin), “vague … forms of speech … have so long passed for mysteries of science” (John Locke)
(s)dark, obscuremarked by difficulty of style or expression“much that was dark is now quite clear to me”, “those who do not appreciate Kafka's work say his style is obscure”
(s)hidden, obscuredifficult to find“hidden valleys”, “a hidden cave”, “an obscure retreat”
(s)obscure, unknown, unsungnot famous or acclaimed“an obscure family”, “unsung heroes of the war”
(s)obscure, unnoticeablenot drawing attention“an unnoticeable cigarette burn on the carpet”, “an obscure flaw”
(s)apart, isolated, obscureremote and separate physically or socially“existed over the centuries as a world apart”, “preserved because they inhabited a place apart” (W.H.Hudson), “tiny isolated villages remote from centers of civilization”, “an obscure village”