Dictionary Definition:
sahásra n. (rarely) m. (perhaps fr. 7, sa + hasra = Gk. ? for ? ; Pers. haśār) a thousand [1195, 2] (with the counted object in the same case sg. or pl., e.g. sahasreṇa bāhunā, 'with a thousand arms' Hariv
• sahasraṃ bhiṣajaḥ, 'a thousand drugs' RV
• or in the gen., e.g. dv-sahāsre suvarṇasya', two thousand pieces of gold' Rājat
• catvāri sahasrāṇ varṣāṇam', four thousand years' Mn
• sometimes in comp., either ibc., e.g. yuga-sahāsram, 'a thousand ages' Mn., or ifc., e.g. sahāsrâśvena, 'with a thousand horses'
• sahasram may also be used as an ind., e.g. sahasram riṣibhiḥ, 'with a thousand Ṛishis' RV
• with other numerals it is used thus, ekâdhikaṃ sahasram, or eka-sahasram', a thousand + one', 1001
• dvyadhikaṃ s○, 'a the + two', 1002
• ekādatâdhikam' sahasram or ekādaśaṃ s○ or ekādaśa-s○, 'a thousand + eleven or 'a thousand having eleven', 1011
• viṃśaty-adhikaṃ s○ or vimaṃ s○, 'a thousand + twenty', 1020
• dve sahasre or dvi-sahacram, 'two thousand
• trīṇi sahacrāṇi or tri-sahasram, 'three thousand' &c.) RV. &c. &c
• a thousand cows or gifts (= sahasraṃ gavyam &c., used to express wealth
• sahasraṃ śatâśvam, 'a thousand cows and a hundred horses' ŚāṅkhŚr.) RV. VS. ŚBr. (in later language often= '1000 Paṇas, e.g. Mn. viii, 120 ; 336 &c.)
• any very large number (in Naigh. iii, 1 among the bahu-nāmāni
• cf. sahasra-kiraṇa &c. below)
• mf(ī)n. a thousandth or the thousandth (= sahasra-tama which is the better form
• Pāṇ. 5-2, 57)