Electroweak is the term for a type of interaction of Particles that encompasses both Electromagnetic forces and the Weak Force, i.e., that the two forces are two forms of an Electroweak Force. In other words a single theory that explains both forces.
The concept of the Weak Force was formulated earlier as an explanation for some Radioactive phenomena, e.g., Beta Decay.
The two other forces of nature besides electroweak are the Strong Force and Gravity. Theories that extend electroweak to include the strong force are called Grand Unified Theories or GUTs. Numerous candidate theories have been developed but none have been proved or widely accepted.