The Collaborative International Dictionary of English v.0.48:

Episcopate \E*pis"co*pate\, n. [L. episcopatus, fr. episcopus:
   cf. F. ['e]piscopat. See Bishop.]
   1. A bishopric; the office and dignity of a bishop.
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   2. The collective body of bishops.
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   3. The time of a bishop's rule.
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The Collaborative International Dictionary of English v.0.48:

Episcopate \E*pis"co*pate\, v. i. [imp. & p. p. Episcopated;
   p. pr. & vb. n. Episcopating.]
   To act as a bishop; to fill the office of a prelate. [Obs.]
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         Feeding the flock episcopating.          --Milton.
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WordNet (r) 3.0 (2006):

episcopate
    n 1: the term of office of a bishop
    2: the territorial jurisdiction of a bishop [syn: diocese,
       bishopric, episcopate]
    3: the collective body of bishops [syn: episcopacy,
       episcopate]
    4: the office and dignity of a bishop [syn: bishopry,
       episcopate]