four notes in place of three

In a duple meter such as 2/4 or 4/4, when three notes take the place of two we call that a triplet.  Got it.  What about in a triple meter when four notes take the place of three?  I am trying to learn an Irish jig which is in 6/8 time, and in three places there are four eighth notes taking the place of three.  What is that called? (My next question is going to be how to indicate that in Tabledit, but first things first.)