WordReference English-Spanish Dictionary © 2015:

Principal Translations
en primer lugar loc advlocución adverbial: Unidad léxica estable formada de dos o más palabras que funciona como adverbio ("en vilo", "de seguido", "a quemarropa"). (antes que nada)first of all exprexpression: Prepositional phrase, adverbial phrase, or other phrase or expression--for example, "behind the times," "on your own."
  in the first place advadverb: Describes a verb, adjective, adverb, or clause--for example, "come quickly," "very rare," "happening now," "fall down."
  firstly advadverb: Describes a verb, adjective, adverb, or clause--for example, "come quickly," "very rare," "happening now," "fall down."
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'en primer lugar' found in these entries
In the Spanish description:
English:

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