They were known as the Warlocks when they started but found out there was another band with the ame name so spent some time tryng to decide on a new name.
from wikipedia..According to Phil Lesh, in his biography (pp. 62), ...[Jerry Garcia] picked up an old Britannica World Language Dictionary...[and]...In that silvery elf-voice he said to me, 'Hey, man, how about the Grateful Dead?' The definition there was the soul of a dead person, or his angel, showing gratitude to someone who, as an act of charity, arranged their burial.
apparently bill Kreutzman and bob weir weren't to happy with the new name at first.
graeme
p.s. Phil's autobiography 'searching for the sound' is a great read as is Dennis Mcnally's 'a long strange trip' if you're interested in the history of the band. naturally, Ron and Susan get a mention ;-)