helio-, heli-

(Greek: sun)

heliometry (s) (noun), heliometries (pl)
The use of a telescope with a movable split-lens objective, primarily to measure the angular distance between two stars; originally used to measure the diameter of the sun.
heliopathy (s) (noun), heliopathies (pl)
A physical injury from too much exposure to sunlight.
heliopause (s) (noun), heliopauses (pl)
1. The outer boundary of the sun where the solar or interplanetary magnetic environment gives way to the interstellar: In astronomy, the heliopause is the outside edge or boundary of the heliosphere, the part of our solar system that's influenced by the sun.

The orbits of all the major planets, including Earth's, lie well within the heliopause.

Astronomers have various theories about what happens beyond the heliopause, at such a far distance from the sun that solar wind doesn't affect anything.

Inside the heliopause is the heliosphere, and everything outside of the heliopause is considered interstellar space.

2. Etymology: The word heliopause is rooted in the Greek word for "sun," helios, and the Latin pausa, "a halt, a stop, or a cessation."
heliophil (s) (noun), heliophils (pl)
Any creature that lives or thrives in full sunlight.
heliophile (s) (noun), heliophiles (pl)
Any living creature or vegetation that is well-adapted to or thriving in full sunlight conditions.
heliophilic (adjective), more heliophilic, most heliophilic
A reference to any organism or plants which are living, well-adapted to, or thriving in full sunlight.
heliophilous (adjective), more heliophilous, most heliophilous
1. In biology, a reference to the thriving of plants and animals in sun-light or under conditions of high-light intensity.
2. A situation in which some desert organisms have adapted to both strong sunlight and to drought.
heliophily (s) (noun), heliophilies (pl)
The living or existence of living plants and animals that are adapted to, and thriving well in an environment of sunshine.
heliophobe (s) (noun), heliophobes (pl)
1. In biology, a plant that is intolerant of full sunlight and grows best in the shade.
2. In medicine, anyone who is abnormally sensitive to or has an exaggerated fear of the rays of the sun.
heliophobia (s) (noun), heliophobias (pl)
An irrational fear of sunlight or an abnormal sensitivity to the effects of sunlight resulting in a strong aversion to being exposed to the sun: In some cases, heliophobia may be influenced by the many warnings that people hear about skin cancer which can develop by being in the sun.
A strong aversion to sunlight.
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heliophobic (adjective), more heliophobic, most heliophobic
A reference to someone who has an exaggerated avoidance of the sun's rays: Linda, according to the doctor's explanation that she was heliophobic, definitely shunned the bright beams of light by wearing dark glasses or shades at all times and even stayed inside whenever the Sol was out.
An abnormal fear of the sun.
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heliophyll (s) (noun), heliophylls (pl)
The leaves of plants which require full sunlight in order to survive and to thrive.
A reference to plants that have leaves that can tolerate full sunlight.
A plant that flourishes under conditions of full sunlight.
A descriptive reference to a plant that flourishes under conditions of full sunlight.

Related "sun" word family: sol-.