Combat Sports Glossary & Rules Guide (Boxing / MMA / Kickboxing)

Words like "TKO," "P4P" and "super bantamweight" come up constantly in fight broadcasts and reporting. Learn them once and watching gets a lot richer. This page is the hub for the core terms and rules of boxing, MMA and kickboxing — each term is covered in depth, one term per explainer, in the linked pages below.

KIAI is a neutral outlet: we run no referral or affiliate links to any promotion or stream. Definitions here follow unified rules and the published material of the relevant governing bodies.

How fights end (KO, TKO, decision)

There are three broad ways a fight is decided. A KO (knockout) is when a fighter is down and cannot beat the referee's count. A TKO (technical knockout) is when the referee, ringside doctor or corner decides a fighter can no longer continue. A decision is when the scheduled rounds finish and the judges' scorecards determine the winner. KO and TKO look similar, but the line is who stopped the fight.

→ Read more: What is a TKO? How it differs from a KO

How rankings work (P4P)

Separate from the per-division rankings, there is a cross-divisional measure called pound-for-pound (P4P). It asks a hypothetical: if every fighter weighed the same, who would be the best? — a way to compare fighters across weight classes. Crucially, it is editorial opinion, not an official title.

→ Read more: What is pound-for-pound (P4P)? Meaning and how it works

Weight classes

Combat sports split fighters into weight classes to keep size fair. Boxing has 17 standard divisions, each with a weight limit. Kickboxing, by contrast, has no single governing body — divisions and champions differ by promotion.

→ Boxing: Boxing weight classes & limits — full chart (2026) → Kickboxing: Kickboxing divisions & rankings 2026, by promotion

Putting the terms to use

Knowing the terms changes how you read a card. Each fighter's record (W-L-D), KO rate, next fight and divisional ranking live on our rankings and individual fighter pages. This guide will keep adding explainers — decision types (UD/SD/MD), doctor stoppage / RSC and more.