abuilding

adjective2

1. •
   (no longer used) Being built or under construction, as a structure or a vessel.

   • It [the monastery of St. Lawrence in Escorial] cost eight millions; it was twenty-four years abuilding, and the founder himself saw it furnished and enjoyed it twelve years after, […] — 1913
2. •
   (no longer used) Developing or arising, as a trend or an idea.

   • This may signify much; among other things that the courtesan is creeping into social favor—even that a new code of morals is now abuilding, in which she will be the grand exemplar. — 1898