ث ب یth-b-y
(ض) ثَبٰى يَثْبِيْ ثَبْيًاthabā yathbī thabyan: to gather, to collect.
ثُبَةthubah pl. ثُبَات وَثُبِيْنthubāt wa-thubīn: a group, a band; separate detachments. The lexicographers say that the original form is ثُبَيthubā and the final radical is elided, which is why it appears in the plural. Only once in the Quran: ﴿فَانْفِرُوْا ثُبَاتٍ أَوِ انْفِرُوْا جَمِيْعًا﴾ (An-Nisāʾ 4:71) — i.e. go forth in separate detachments or all together.