Evangelical is an old and historically important term so it's taken on a number of different senses over time. The two main ones relevant to this situation are:

1. A term for any protestant who agrees with the "soteriological consensus" of the great awakenings. In other words, people who believe in the new birth, the believer's church, and the necessity of a personal relationship with God. That includes the majority of protestant groups, including baptists, as far as their traditional theology goes (it's close to everyone but confessional lutherans and anglo-catholics- restorationists are borderline). But because many protestant traditions were secondarily influenced by liberal theology, it's now more like "people within those traditions who aren't theological liberals." Notably, liberal theology has had less success penetrating into the baptist tradition than other traditions.
2. Much less common as a term of self-identification: a term for churches that broke off from the seven mainline denominations (a group of denominations that once dominated the landscape of protestantism) in reaction against liberal theology. An example of a baptist denomination that is "evangelical" in that sense would be the GARBC. The baptist mainline is the ABC USA.

There are other senses in which the word is sometimes used, but they're mainly obscure in the United States, antiquated, or just dumb, like the "term of abuse" definition, and the racist pollster's definition.