A fugitive from justice is a person who is hiding from law enforcement.
If this is a federal case, the relevant statutory definition would be in 18 USC 1073 which defines "fugitive from justice" as:
"Whoever moves or travels in interstate or foreign commerce with
intent either (1) to avoid prosecution, or custody or confinement
after conviction, under the laws of the place from which he flees,
for a crime, or an attempt to commit a crime, punishable by death
or which is a felony under the laws of the place from which the
fugitive flees, or (2) to avoid giving testimony in any criminal
proceedings in such place in which the commission of an offense
punishable by death or which is a felony under the laws of such
place, is charged, or (3) to avoid service of, or contempt
proceedings for alleged disobedience of, lawful process requiring
attendance and the giving of testimony or the production of
documentary evidence before an agency of a State empowered by the
law of such State to conduct investigations of alleged criminal
If it's a state case, it's going to be a very similar definition under the relevant state statute. Basically this means they think he moved to the other state to avoid the police because he didn't want to get arrested on this warrant, and that is itself a crime.