The Collaborative International Dictionary of English v.0.48:

Nigh \Nigh\ (n[imac]), a. [Compar. Nigher (n[imac]"[~e]r);
   superl. Nighest, or Next (n[e^]kst).] [OE. nigh, neigh,
   neih, AS. ne['a]h, n[=e]h; akin to D. na, adv., OS. n[=a]h,
   a., OHG. n[=a]h, G. nah, a., nach to, after, Icel. n[=a] (in
   comp.) nigh, Goth. n[=e]hw, n[=e]hwa, adv., nigh. Cf. Near,
   Neighbor, Next.]
   1. Not distant or remote in place or time; near.
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            The loud tumult shows the battle nigh. --Prior.
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   2. Not remote in degree, kindred, circumstances, etc.;
      closely allied; intimate. "Nigh kinsmen." --Knolles.
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            Ye . . . are made nigh by the blood of Christ.
                                                  --Eph. ii. 13.
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   Syn: Near; close; adjacent; contiguous; present; neighboring.
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WordNet (r) 3.0 (2006):

nighest
    adv 1: (superlative of `near' or `close') within the shortest
           distance; "that was the time he came nearest to death"
           [syn: nearest, nighest, closest]