1843, from German Zollverein, literally "customs union," from Zoll "toll" (see toll (n.)) + Verein "union," from vereinen "to unite," from ver- + ein "one" (from PIE root *oi-no- "one, unique").
Entries linking to zollverein
toll n.
"tax, fee," Old English toll "impost, tribute, passage-money, rent," variant of toln, cognate with Old Norse tollr, Old Frisian tolen, Old High German zol, German Zoll, probably an early Germanic borrowing from Late Latin tolonium "custom house," classical Latin telonium "tollhouse," from Greek teloneion "tollhouse," from telones "tax-collector," from telos "duty, tax, expense, cost" (from suffixed form of PIE root *tele- "to lift, support, weigh;" see extol) For sense, compare finance.
On another theory it is native Germanic and related to tell (v.) on the notion of "that which is counted." Originally in a general sense of "payment exacted by an authority;" meaning "charge for right of passage along a road" is from late 15c.
ver-
German prefix "denoting destruction, reversal, or completion" [Watkins], from Proto-Germanic *fer-, *far-, from PIE root *per- (1) "forward," hence "through."
*oi-no-
Proto-Indo-European root meaning "one, unique."
It forms all or part of: a (1) indefinite article; alone; an; Angus; anon; atone; any; eleven; inch (n.1) "linear measure, one-twelfth of a foot;" lone; lonely; non-; none; null; once; one; ounce (n.1) unit of weight; quincunx; triune; unanimous; unary; une; uni-; Uniate; unilateral; uncial; unicorn; union; unique; unison; unite; unity; universal; universe; university; zollverein.
It is the hypothetical source of/evidence for its existence is provided by: Greek oinos "ace (on dice);" Latin unus "one;" Old Persian aivam; Old Church Slavonic -inu, ino-; Lithuanian vienas; Old Irish oin; Breton un "one;" Old English an, German ein, Gothic ains "one."