In Super Mario World and Super Mario Maker, holding jump after reaching peak of the jump arc will slow down your fall a little bit (even if you don't have cape). Regrab uses this by letting player make a smaller jump by letting go of jump button before the peak, BUT then re-pressing the jump button later to slow down the fall - thus allowing a jump arc that isn't otherwise possible, with short rise but long descent. So re-pressing the button - that's the 'regrab' part.
This can also be combined with other tricks, for example there are versions of a shell jump and a pow drop with regrabs in some versions of Mario Maker.
This kaizo level has a very hard jump. If I jump too high I hit the spikes, but if I fall too fast I will hit the grinder saw - you need a really precise regrab to just barely make it.
-Hey, the Quora AI bot says that regrab is about letting go and grabbing a vine?
-That is complete nonsense.
The act of reposting on instagram. It involves screen-shotting someones else's original post, and then reposting it using the hashtag #regram and acknowledging the source of the original instagram posting.
So called 'illegal' posts are those that are 'regrammed' without acknowledgement of the original creator or w/o using the #regram hashtag
Our 22 year old intern just taught me how to 'regram' - and now I feel like a useless technophobe, i guess it kind of the same way i made my parents feel about their inane questions on how to work email.