related discussion: hail-fellow-well-met stuff
related discussion: Hail fellow, well met!


NOAD (2001):
hail-fellow-well-met - (adj.) showing excessive familiarity: Harold was accustomed to hail-fellow-well-met salesmen.

Chambers:
hail-fellow-well-met - (adj) friendly and familiar, especially in an overpowering or offensive way.

AHD2 (1985):
hail-fellow /also/ hail-fellow-well-met - (adj.) Heartily friendly and congenial.

Webster's 3rd unabridged (1961):
¹hail-fellow /or/ hail-fellow-well-met - (adj) heartily informal: COMRADELY {extended a hail-fellow hand —Edith Wharton} {a giant of a man — rough, hearty, violent, hail-fellow-well-met ...}
²hail-fellow /or/ hail-fellow-well-met (n, pl) hail-fellows /or/ hail-fellows-well-met 1: a boon companion: PAL {all were hail-fellows-well-met by the time the convention opened ...} 2: the quality or state of comradeship {there was a hail-fellow-well-met, a camaraderie, a gregariousness about it ...}

Random House (1966):
hail-fellow - n. 1. Also, hail fellow, hail-fellow well met. a spiritedly sociable person; jolly companion. —adj. 2. sociable; heartily genial: His hail-fellow manner helped him to advance in the sales force.

Pons-Collins:
hail-fellow-well-met - (adj) plumpvertraulich;
he tries to be hail-fellow-well-met with everyone - er versucht, sich bei allen anzubiedern

Oxford-Duden:
hail² - ... 4: ... hail-fellow-well-met - kumpelhaft;
be hail-fellow-well-met with someone - jmdn. kumpelhaft behandeln

I've never heard 'hail-fellow' alone, or either form used as a noun. To me the entries from the older dictionaries are outdated, but I include them for the sake of completeness.

The NOAD and Chambers definitions match current usage in my experience.