The Collaborative International Dictionary of English v.0.48:

Intercommunicate \In`ter*com*mu"ni*cate\, v. i.
   To communicate mutually; to hold mutual communication.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Intercommunicate \In`ter*com*mu"ni*cate\, v. t.
   To communicate mutually; to interchange. --Holland.
   [1913 Webster]

WordNet (r) 3.0 (2006):

intercommunicate
    v 1: be interconnected, afford passage; "These rooms
         intercommunicate"
    2: transmit thoughts or feelings; "He communicated his anxieties
       to the psychiatrist" [syn: communicate, intercommunicate]

Moby Thesaurus II by Grady Ward, 1.0:

30 Moby Thesaurus words for "intercommunicate":
   adhere, be in connection, be in contact, clinch, cohere,
   come together, commerce with, commune with, communicate, connect,
   converge, converse, deal with, embrace, grow together,
   hang together, have dealings with, have intercourse,
   have truck with, hold communication, hold together, interchange,
   join, knit, meet, merge, speak, talk, traffic with, unite