Indubitable, a.
Etymology: [L. indubitabilis: cf. F. indubitable. See In- not, and Dubitable.]
Not dubitable or doubtful; too evident to admit of doubt; unquestionable; evident; apparently certain; as, an indubitable conclusion. -- n.
That which is indubitable.
Syn. -- Unquestionable; evident; incontrovertible; incontestable; undeniable; irrefragable.
Shades of meaning
Fernald has no entry of its own for indubitable; he lists it under evident.
He lists it without comment; the entries above explain its neighbors.