Amongst means in the middle of a group, in more formal use. Amongst friends, amongst other things, divided amongst them.
It means exactly what among means, and the difference is register: amongst is commoner in British writing and sounds slightly literary, and American writing has largely dropped it. The t on the end is a later addition, as in whilst and amidst.
1prepositionamongstIn the middle of a group.
“The cottage was hidden amongst tall trees.”
amongst is a position.
From amongs, an old genitive of among, plus an added t, as in whilst and amidst.
Old English
ongemang
English, today
amongst
Built from
From amongs + t, from among + s. by surface analysis, among + -st. Root among from Old English ongemang, from on (“in”) + gemang (“assemblage, mingling”).
Etymology from Wiktionary, CC BY-SA