Definition of "hightum"

One was of superfine material; in this she appeared among her "quality friends," and it went by the name of "Hightum."

1876, “Hightum, Tightum, and Scrub!”, in The Leisure Hour‎

For one of Lucia's quaint ideas was to divide dresses into three classes, "Hightum," "Tightum" and "Scrub." "Hightum" was your very best dress […]

1920, E. F. Benson, Queen Lucia‎