obscurecer
= obscure, overshadow, dim, darken.
Ex: A pseudonym is the name assumed by an author to conceal or obscure his or her identity.
Ex: And when the maintenance of structure is permitted to overshadow the functional performance of the institution, it will move toward extinction.
Ex: At first, analyzing the way he went about his work eroded his confidence, threw him off balance, dimmed some of his energetic spirit.
Ex: Gum arabic containing inks darken more than inks without it.
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* obscurecerse = turn + dark.