Source : Webster's Revised Unabridged Dictionary (1913)

Upstream \Up*stream"\, adv.
   Toward the higher part of a stream; against the current.

Source : WordNet®

upstream
     adj : in the direction against a stream's current [ant: {downstream}]
     adv 1: toward the source or against the current [syn: {upriver}]
            [ant: {downriver}, {downriver}]
     2: against the current; "he swam upstream"

Source : Free On-Line Dictionary of Computing

upstream
     
         Fewer {network} {hops} away from a {backbone} or
        {hub}.  For example, a small {ISP} that connects to the
        {Internet} through a larger ISP that has their own connection
        to the backbone is {downstream} from the larger ISP, and the
        larger ISP is {upstream} from the smaller ISP.
     
        (1999-08-05)