Continuing the look at synonyms through the eyes of the etymologist, this time it is the letter L and light.
Clearly there are two senses for the word - opposite of 'dark' and also of 'heavy'. In the illumination sense it is a noun which has not changed in meaning since the days of Proto-Indo-European some five thousand plus years ago where leuk also meant 'brightness' as well as 'light'. As an adjective, the term is also from Proto-Indo-European but this time the root is legwh meaning 'not heavy', or 'having little weight'. Note when the term first came to Old English it was used in the sense of 'not heavy' but also as 'easy to do, trifling, quick, agile'. Sticking with synonyms of the noun first, we come to ....
Bright is another from Proto-Indo-European where bhereg also meant 'shine, white'. Note the use of 'bright' in the sense of 'intelligent, quick-witted' is unrecorded prior to 1741.
Shine is likely from the Proto-Indo-European root skai meaning both 'shine' and ....
Gleam is another of Proto-Indo-European origin where ghel was used in the sense of 'shine' (and also the origin of the word for the shiniest of metals 'gold'). It is not as confusing as it seems but does take a little thinking about - simply two words with the same meaning, which have evolved into synonyms. Sadly we have no idea why that ancient language had two words for the same thing as earlier languages are unknown.
Glow shares a Proto-Indo-European root with 'gleam' in ghel. While the above came to English through the Saxons,'glow' reached our shores through the Norsemen.
Lustre came to English from Old French, to there through the Latin family of languages and ultimately Proto-Indo-European leuk 'brightness'.
Radiant shares an origin with, of all things, 'radiation', itself sharing a root with 'radius'. This Latin word radius would be difficult to beat when it comes to versatility, for it was used to mean 'staff, stake, rod, spoke of a wheel, ray of light, beam of light, radius of a circle'. Unsurprisingly the origins of this word are a mystery. Note, not until 1610 was this used to describe the bones of the forearms.
Glare is from the verb and, once again, can be traced to the Proto-Indo-European root ghel.
Brilliance, a form of 'brilliant', came to English from French and prioer to that Latin. For those who stress the word by adding an additional syllable at the beginning - ber-rilliant - they may be interested to know that berillare was the original Latin form and was used to mean 'to shine like beryl' and from the Latin name of the precious stone beryllus.
Wispy is one of the very few synonyms for the adjective, itself indicative of the comparatively recent use of the word in this light (pun intended). Derived from 'wisp', this connected to Middle Low German and Middle Dutch wispel meaning 'a measure of grain'.
Thin has come to English through the Germanic languages and is ultimately from Proto-Indo-European ten 'to stretch'.
What may also be of interest is the first known usage of terms using 'light' as one elemt. 'To make light of' first recorded in 1520; 'see the light' was in use by 1680s; 'out like a light' as recent as 1934; 'nightlight' is from 1851; 'lightbulb' comes from the 1920s (and jokes about lightbulbs have been told since 1971); 'light show' (as in a rock concert) first appears in 1966; 'lightfingered' is first seen in the 1540s; and 'blacklight' first used in 1927. One phrase, first recorded in the 1590s, has fallen out of usage and that is 'light-skirts', sais to describe a 'woman of easy virtue'.