The act of cuddling and other such public displays of affection (PDA) in an open area. Nesting is commonly done spontaneously with someone you don't particularly know very well.
Group nesting is called a Nest Fest.
This act can lead to Burrowing. Burrowing can lead to babies.

The act of leaving small stashes of your things in various places in an random and unorganized manner.

To go to the nest. To retreat to the place hawks live, the nest. To stay with other hawks at the nest;

The act of draping sheets of toilet paper between the toilet seat and toilet bowl until one has created a net in which to catch one's poop so that no defecation sound ("poop plunk") is audible to potential boyfriends sitting in the other room.

Another name for a womens cleavage.

Defined on ABOheadcanons (A/B/O, Alpha/Beta/Omega), Nesting is more of a softer action where an Omega takes things that make them comfortable and surround them-self with it during heat. This could be something that smells like their partner, or it could be something that calms the Omega. Usually, things found in nests are soft.

Nesting is when a bird is making a nest and the process of laying the eggs and interbate them.