Synonyms for Intimate (same or very similar meaning)
WordNet sense 1 (someone to whom private matters are confided):
confidant
WordNet sense 2 (innermost or essential):
inner, internal
WordNet sense 3 (belonging to a thing by its very nature):
intrinsic
WordNet sense 4 (having or fostering a warm or friendly and informal atmosphere):
cozy, informal
WordNet sense 5 (characteristic of or befitting a friend):
friendly
WordNet sense 6 (thoroughly acquainted through study or experience):
knowledgeable, versed
WordNet sense 7 (having experience; having knowledge or skill from observation or participation):
experienced, experient
WordNet sense 8 (imply as a possibility):
suggest
WordNet sense 9 (give to understand):
adumbrate, insinuate
WordNet sense 10 (having mutual interests or affections; of established friendship):
familiar
WordNet sense 11 (close in relevance or relationship):
close
From the ODE community, based on WordNet
add/edit