direct

Proceeding without deviation or interruption.

Straight; not crooked, oblique, or circuitous; leading by the short or shortest way to a point or end.

Straightforward; sincere.

Immediate; express; plain; unambiguous.

In the line of descent; not collateral.

(astronomy) In the direction of the general planetary motion, or from west to east; in the order of the signs; not retrograde; said of the motion of a celestial body.

(political science) Pertaining to, or effected immediately by, action of the people through their votes instead of through one or more representatives or delegates.

(aviation, travel) having a single flight number.