A form is an array of interlocking vertical and horizontal words which has a boundary tracing out a simple geometric shape. Word squares (of any size) are perhaps the most well-known examples of forms. A wide variety of different forms were constructed between 1870 and 1905. One of the more elaborate forms is a Hallow Diamond, first devised by L. M. N. Terry in 1904 (A Key to Puzzledom, William W. Delaney, 1906). All but one of the words or phrases in the form below are given in boldface in Webster's Second Edition, or are plurals of such entries; the exception, VANITES, can be found in Webster's First Edition.
Peterson, Palmer C.
"A Hollow Diamond,"
Word Ways: Vol. 4
, Article 10.
Available at: http://digitalcommons.butler.edu/wordways/vol4/iss2/10