A brilliant example of etymological semantic motivation present in Ukrainian and Byelorussian (or Polish) names of months. Cf. січень (сніг січе), лютий (мороз лютує), березень (береза сік пускає), квітень (перші квіти – проліски з'являються і зацвітають), липень (липа зацвітає), серпень (серпами жали і жнуть збіжжя).
Semantical1у motivated lexical units constitute in English about 10 % and in Ukrainian about 7.4 % of their total motivated lexicons.
Compound words are either morphologically or semantically motivated in the contrasted languages. Their motivation is morphological if the meaning of the whole is based on the direct meaning of the components (e.g., headache is pain in the head, air-crew is a crew of an aircraft; after-effect effect that occurs after some action; to blackboard to write on a black board.), and semantic if the combination of components is used figuratively (headache – anything or anyone very annoying, good-neighbourhood being near good neighbours, classroom (room for classes or for schoolchildren), drawbridge, halfpenny, landowner, mine thrower (thrower of mines), note-book (book for notes), self-defense, a schoolboy, Zululand (land of the Zulus), etc.
Or in Ukrainian: вільнодумець (думає про волю), добродійник (робить добро), домовласник (володіє домом), електродояр, кожум'яка (мне шкуру тварин), кораблеводіння, користолюбство (любить корисливість), лизогуб (облизує губи), лісовоз, маслоробня, марнотратство (витрата чогось без користі, марно), etc.
Generally, however, a great many words in English, Ukrainian and in other languages have no clear motivation, i. e. their etymology remains obscure, far from explicable at present. It has been lost in the course of semantic development of these words. As a result, one can not say why the "sun" is named the sun and the "head" or the "heart" has been named this way and not otherwise. Because of the obscure etymology most words and some collocations/idiomatic expressions remain non-motivated in the contrasted languages. In other words, their motivation is impossible to identify nowadays on the basis of their componential meanings.