Namo -- Homage (perhaps from a root meaning to bend)
Tassa -- to him
Bhagavato -- usually translated "blessed one" or "fortunate one"
Arahato -- I'm not sure whether this means deserving (perhaps deserving of homage) or fully enlightened (see also here)
Samma Sambuddhasa -- see SN 22.58; see also the definition for sammā
As to origin the ...