In any term (including games), Blind jump makes reference to a jump done by someone (a person or character) without knowing where they will fall, being the person's fault (for not looking before) or because something external didn't allow him to know exactly.
Blind jumps are recurrent on Mario games where the level size allows a "y" axis movement, the screen is placed in a way that the player doesn't knows where will he fall. The blind jumps on games are always present by creator's fault who didn't considered them using the players' perspective.
For PG community, a level could have a bad reception if it counts with space which cannot be seen easily by screen and causes the player to make a blind jump, more if the space below counts with death tiles.
In order to avoid blind jumps actions, the level maker must include coins to guide the user where to go.