In law, an allonge is a slip of paper attached to a negotiable instrument to hold endorsemenets if the document itself is unable to hold any more.

In the sport of fencing, an allonge is a thrust, pass, or lunge.

I think you mean allonge, which means to elongate or stretch out.

These are ballet terms. Because ballet became formalized in France, a significant part of ballet terminology is in the French language.

You can say "allonge-toi avec moi" in French to ask someone to lay down with you.

Allonge is from French allonger, "to draw out". Essentially, it is a sheet of paper attached to a bill to accommodate further endorsements when the original bill is full.