Borrowed from Assamese অসম (oxom), of unclear origin, but generally agreed to be related to Ahom. More at Etymology of Assam on Wikipedia.Wikipedia
Meanings
(abbreviation, alt-of, ellipsis, uncountable) Ellipsis of Assam tea, tea from or similar to that grown in Assam; any tea made from the broad-leaf Assam variety of tea (C. sinensis var. assamica).
He took the cup in both hands and sipped. It was their favourite blend of Assam, dark and heady and strong. 2022, R. F. Kuang, Babel, HarperVoyager, page 360:
bo ཨཱསཱམ (state in northeastern India) · cmn 阿薩姆邦 /阿萨姆邦 (state in northeastern India) · as অসম (state in northeastern India) · es Asam (state in northeastern India) · fr Assam (state in northeastern India) · ja アッサム (state in northeastern India) · bn আসাম (state in northeastern India) · kn ಅಸ್ಸಾಂ (state in northeastern India) · ta அசாம் (state in northeastern India) · fi Assam (state in northeastern India) · mr आसाम (state in northeastern India) · eo Asamo (state in northeastern India) · hi असम (state in northeastern India) · lv Asama (state in northeastern India) · de Assam (state in northeastern India) · ace Assam (state in northeastern India) · el Ασσάμ (state in northeastern India) · th อัสสัม (state in northeastern India) · pnb آسام (state in northeastern India) · aho 𑜉𑜢𑜤𑜂𑜫 𑜓𑜤𑜃𑜫 𑜏𑜤𑜃𑜫 𑜁𑜪 (state in northeastern India) · ug اسام (state in northeastern India) · hi आसाम (state in northeastern India) · pt Assam (state in northeastern India) · ka ასამი (state in northeastern India) · et Assam (state in northeastern India) · hu Asszám (state in northeastern India) · he אסאם (state in northeastern India) · dv އާސާމު (state in northeastern India) · hy Ասսամ (state in northeastern India) · cs Ásám (state in northeastern India) · ml ആസാം (state in northeastern India) · or ଆସାମ (state in northeastern India) · war Assam (state in northeastern India) · bn অসম (state in northeastern India) · ru Асса́м (state in northeastern India) · uk Асса́м (state in northeastern India) · pam Assam (state in northeastern India) · bg Аса́м (state in northeastern India) · ko 아삼 (state in northeastern India) · el Άσαμ (state in northeastern India) · fa آسام (state in northeastern India) · gu આસામ (state in northeastern India) · ar أَسَام (state in northeastern India) · lt Asamas (state in northeastern India) · ca Assam (state in northeastern India) · ccp 𑄃𑄥𑄟𑄴 (state in northeastern India) · pa ਅਸਾਮ (state in northeastern India) · pt Assã (state in northeastern India) · te అసోం (state in northeastern India) · nl Assam (state in northeastern India) · syl ꠀꠡꠣꠝ (state in northeastern India) · ur آسام (state in northeastern India) · my အာသံ (state in northeastern India) · es Assam (state in northeastern India)