The Collaborative International Dictionary of English v.0.48:

Attar \At"tar\, n. [Per. 'atar perfume, essence, Ar. 'itr, fr.
   'atara to smell sweet. Cf. Otto.]
   A fragrant essential oil; esp., a volatile and highly
   fragrant essential oil obtained from the petals of roses.
   [Also written otto and ottar.]
   [1913 Webster]

WordNet (r) 3.0 (2006):

attar
    n 1: essential oil or perfume obtained from flowers [syn:
         attar, atar, athar, ottar]

Moby Thesaurus II by Grady Ward, 1.0:

29 Moby Thesaurus words for "attar":
   ambergris, ambrosia, aromatic, aromatic gum, aromatic water,
   attar of roses, balm, balm of Gilead, balsam, bay oil,
   bergamot oil, champaca oil, civet, essence, essential oil, extract,
   fixative, heliotrope, jasmine oil, lavender oil, musk, myrcia oil,
   myrrh, parfum, perfume, perfumery, rose oil, scent, volatile oil