Definition of "dilatation"
noun
usually uncountable, plural dilatations
The act of dilating; expansion; an enlarging on all sides; the state of being dilated
Quotations
These [boys being groomed as prostitutes] are sold by their parents (sometimes stolen from them), about the age of 4, and educated, while they are also subjected to a special physical training, which includes massage of the gluteal regions to favor development, dilatation of the anus, and epilation (which is not, however, practised by Chinese women).
1927, Havelock Ellis, Studies in the Psychology of Sex, Volume 2 (of 6)