H7677. shabbathon
שַׁבָּתוֺן noun masculine sabbath observance, sabbatism; — ׳שׁ [Exod 16:23] [10]t. P; usually phrase שַׁבָּתוֺן שַׁבַּת sabbath of sabbatic observance; —
1 of weekly sabbath [Exod 31:15]; [35:2]; [Lev 23:3]; [Exod 16:23] (קֹדֶשׁ שַׁבַּת שַׁבָּתוֺן, probably transposed).
2 day of atonement [Lev 16:31]; [23:32].
3 sabbatical year [Lev 25:4]; compare שַׁבָּתוֺן שְׁנַת [25:5].
4 ׳שׁ alone of feast of trumpets [Lev 23:24], and of first and eighth days of feast of tabernacles [23:39]; [23:39].