He who brings together what He wills, when He wills, where He wills.He who will gather the mankind on the Judgement Day that the reckoning will be established.
He who gathers and puts in order all the creatures in the universe with a perfect harmony. The being that all the praises and virtues gathered on Him.
βIn that is a Sign for those who fear the Penalty of the Hereafter: THAT IS A DAY FOR WHICH MAN- KIND WILL BE GATHERED TOGETHER: THAT WILL BE A DAY OF TESTIMONY.β
(11:103) The Holy Quran

From the root j-m-' with the classical Arabic connotations: to collect, gather up to congregate, gather together to reconcile, connect together, combine, compose, arrange, resolve or settle.
Allah reconciles and unites. He gathers together that which had been dispersed.
He assembles and arranges. He composes, arranges and connects together.
