Both Uses of

relative
in
The War of the Worlds

And not only did the Martians either not know of (which is incredible), or abstain from, the wheel, but in their apparatus singularly little use is made of the fixed pivot or relatively fixed pivot, with circular motions thereabout confined to one plane.†
Chpt 2.2 *

relatively = in comparison to something else

Probably this is due to the relative strength of the earth's gravitational energy.†
Chpt 1.14

Definitions:

(1) (relative as in: the relative importance)
compared with something else (not an absolute value or not complete)
(2) (relative as in: they are relatives)
connected
in various senses, including:
- a person related by blood or marriage -- as in "The hospital won't let me visit her because I'm not a relative."
- a plant or animal related by origin or grouping -- "The closest relative of the dog is the gray wolf."
(3) (relative as in: questions relative to the topic)
related to
(4) (meaning too rare to warrant focus)
meaning too rare to warrant focus:

More specialized and less common senses of the word are found in philosophy, grammar, and music. Consult a comprehensive dictionary if you wish to see those. All senses have to do with relationships.