The Bedford Glossary of Critical and Literary Terms - Ross Murfin 2018
Catalexis (truncation)
Catalexis (truncation): Omission of one or two unstressed syllables in the last foot of a line of verse.
EXAMPLE: The trochaic octameter lines of Edgar Allan Poe’s “The Raven” (1849) sometimes lack the last unaccented syllable, as in the following second line:
Whiĺe Ĭ nóddĕd, néarly̆ náppin̆g, súdden̆lý thĕre cáme ă táppĭng,
Ás ŏf sóme on̆e géntly̆ ráppin̆g, ráppin̆g át m̆y chámbĕr dóor —
Ónly̆ thi̇́s an̆d nóthin̆g móre.