Practical Law UK Glossary 9-107-6966 (Approx. 3 pages)
Glossary
Additional claim
An additional claim is any claim other than a claim by a claimant against a defendant. This includes:
A counterclaim by a defendant against the claimant or against the claimant and another party. (A counterclaim is a claim brought by a defendant in response to the claimant's claim which is included in the same proceedings as the claimant's claim.)
A claim by a defendant against any person (whether a party or not) for contribution or indemnity.
Where an additional claim claim has been made against a person who is not already a party, any claim made by that person against any other person (whether or not already a party).