The Oxford Thesaurus An A-Z Dictionary of Synonyms - secondary adj.

1) less important, unimportant, inessential or unessential, non-essential, non-critical, subsidiary, ancillary, minor, inferior, subordinate: These secondary matters can be dealt with after the important ones. 2) derivative, derived, indirect, second-hand, unoriginal, not original; copied, imitated: His biography of Queen Victoria was based entirely on secondary sources. 3) auxiliary, second-line, backup, extra, reserve, spare, provisional, supporting, supportive, alternate, alternative: We were forced to rely on our secondary defences after the enemy cavalry broke through.