zk-SNARKs vs. Zk-STARKs vs. Bulletproofs: definitions
A class. Parameters according to which it is standard to compare them, are: prover time, verifier time, proof size, requirement of trusted setup, cryptographic assumptions. For "succinctness", the standard definition requires that verification time is sub-linear and proofs are "small".
STARK however, is a name of a specific zk-SNARKS protocol, see any Eli Ben Sasson talk on Youtube for the specific attributes.
I reckon it's because verification time is linear.