Malapropism, and the Mariam Webster Word of the Day

Main Entry: mal·a·prop·ism
Pronunciation: 'ma-l&-"prä-"pi-z&m
Function: noun
Etymology: Mrs. Malaprop, character noted for her misuse of words in R. B. Sheridan's comedy The Rivals (1775)

1: the usually unintentionally humorous misuse or distortion of a word or phrase; especially : the use of a word sounding somewhat like the one intended but ludicrously wrong in the context

Mariam Webster Word of the Day:
enroach \in-KROACH\
[verb]
1 : to enter by gradual steps or by stealth into the possessions or rights of another