Swerve, veer, deviate, depart, digress, diverge mean to turn aside from a straight line or a defined course.
Swerve may refer to a turning aside, usually somewhat abruptly, by a person or material thing or it may suggest a mental, moral, or spiritual turning aside.
Veer is frequently used in reference to a change in the course of a wind or of a ship; often it suggests either a frequent turning this way or that or a series of turnings in the same direction, especially of the wind in a clockwise direction.
In extended use the term commonly implies a change or series of changes of direction or course under an external influence comparable to the wind or a turning aside for a tactical reason (as to avoid an undue influence).
Deviate implies a turning aside from a customary, chosen, allotted, or prescribed course. It is commonly used in reference to persons, or their minds, their morals, and their actions, with the suggestion of a swerving from a norm or standard or from a right or lawful procedure or course.
The next three words of this group usually imply a turning aside from a literal or figurative way (as a path, course, track, or standard) which still continues.
Depart stresses the turning away from and leaving an old path, a customary course, or an accepted type or standard; it may further imply a forsaking of the antiquated, conventional, or traditional or a deviation from what is right, true, or normal.
Digress commonly implies a departure from the subject of one’s discourse that may be voluntary and made with the intent to return or involuntary and the result of an inability to think coherently or to stick to the point to be developed.
Diverge is sometimes used in the sense of depart ,but more typically it suggests a separation of a main, old, or original course or path into two or more courses or paths that lead away from each other.