Definition of "tubular"

As we descended the long wooden stairway that leads from the central tower to the Island of Inchgarvie, the straight and simple outlines of the internal viaduct stood out in sharp contrast to the long sweep of the massive tubular arms of the cantilevers, and the complicated network of the lattice cross girders.

1950 March, H. A. Vallance, “On Foot Across the Forth Bridge”, in Railway Magazine, page 150

It was such a tubular party, Journal! But a few minutes later, I walked up to the Hermosa Beach Pier and left the girls with my things, thinking the totally bitchin' party would continue. But when I got back, they were all gone.

2007, Brian Laesch, The Verge of Psychosis: An Aspiring Actor's Journal