prosiopesis

Etymology
Coined in 1917 by the Danish linguist Jens Otto Harry Jespersen: (from the  preposition ) +  (from ) +, (-sis, suffix forming nouns of action).

Noun

 * 1)  Ellipsis of the beginning of a grammatical construction,  common in informal speech and spontaneous written electronic communication, frequently occurring in stock phrases and interjections.

Coordinate terms

 * apocope, aposiopesis; syncope, *synsiopesis