Wiktionary
abuilding
a. 1 (context archaic excluding US English) Being built or under construction, as a structure or a vessel. (First attested in the mid 16th century.)(R:SOED5: page=10) 2 (context archaic excluding US English) Developing or arising, as a trend or an idea. (First attested in the mid 16th century.)
Usage examples of "abuilding".
My ship abuilding out in the construction orbits was human-designed and human-built, but most of the construction, and all of the drive and communications systems, were adapted from Heechee designs.
GREAT scandal of our Space Station Freedom, abuilding now, is not really how much it will cost.
You will build it so that eight power lines may run into a far-off place called the Yards where this mighty mechanism is abuilding.