piecemeal
Piecemeal (adj) means Done gradually, in separate parts rather than all at once.
Etymology
Came into English via Middle English pecemele, from pece ("piece") plus mele, from Old English mǣlum ("at a time"), the dative plural of mǣl ("time, measure"), which took over from Old English styċċemǣlum ("in pieces, bit by bit, piecemeal; to pieces, to bits; here and there, in different places; little by little, by degrees, gradually"); equivalent to piece plus -meal.