father: a male parent, an ancestor, or, supremely in the New Testament, God himself.
At its root this is the ordinary word for a male parent, the same word a child would use at home. From there it reaches in two natural directions. Looking backward, it names the ancestors a family or a nation descends from, so "the fathers" can mean the patriarchs and the whole line of forebears. Looking outward, it names anyone who stands as a founder or source to others, the way Abraham is called the father of all who believe and a deceiver can be called a father of lies.
The note the New Testament strikes most often, though, is the one that gives the word its weight: God is Father. Jesus speaks of God as "my Father" and teaches his followers to pray "our Father," and the writers after him take up the same address. This is not a stray metaphor but the center of how the New Testament names God, especially in John, where Father and Son describe a bond of love, knowledge, and shared work.
All of these stay recognizably one word rather than splitting into unrelated meanings: a parent, the ones a parent comes from, the one who is source or founder to others, and God as the supreme Father over all. English keeps a single word for the whole range too, which is why the senses sit together here under one entry, sorted by context rather than by a different translation.