Source : Webster's Revised Unabridged Dictionary (1913)

Meantime \Mean"time`\, Meanwhile \Mean"while`\, n.
   The intervening time; as, in the meantime (or mean time).

Meantime \Mean"time`\, Meanwhile \Mean"while`\, adv.
   In the intervening time; during the interval.

Source : WordNet®

meanwhile
     adv 1: at the same time but in another place; "meanwhile, back at
            the ranch..."
     2: during the intervening time; "meanwhile I will not think
        about the problem"; "meantime he was attentive to his
        other interests"; "in the meantime the police were
        notified" [syn: {meantime}, {in the meantime}]