LSJ
[ᾰ] τό, the Hebrew Sabbath, i.e. Rest (δηλοῖ δὲ ἀνάπαυσιν… τὸ ὄνομα J. AJ 1.1.1), LXX Ex. 16.23, al., Ev. Marc. 6.2, al. ; freq. in pl. of the single day, PCair. Zen. 762.6 (iii BC), LXX 4 Ki. 4.23; ὀψὲ σαββάτων Ev. Matt. 28.1; ἡ ἡμέρα τῶν σ. LXX Nu. 15.32, Ev. Luc. 4.16, al. (but ἡ ἡμέρα τοῦ σ. ib. 13.14); heterocl. dat. pl. σάββασι(ν) LXX 1 Ma. 2.38, J. BJ 1.7.3, al., Ev. Marc. 2.23, al., freq. with v.l. σαββάτοις ; but σάββασι is certain in AP 5.159 (Mel.).
2.
period of seven days, week, εἰς μίαν σαββάτων toward the first day of the week, Ev. Matt. 28.1; κατὰ μίαν σαββάτου 1 Ep. Cor. 16.2; πρώτῃ σαββάτου Ev. Marc. 16.9; τῇ μιᾷ τῶν σ. ib. 2, Ev. Jo. 20.1; δὶς τοῦ σ. Ev. Luc. 18.12.
3. Σαβάτ, the 11th month of the Hebr. year, nearly = February, LXX 1 Ma. 16.14.
Liddell-Scott-Jones, Greek-English Lexicon (9th ed., 1940)