Exceptional

Synonymic differentiation
It must be noted that synonyms may influence each other semantically in two diametrically opposite ways: one of them is dissimilation or differentiation, the other - the reverse process , i.e. assimilation.
Many words now marked in the dictionaries as "archaic" or "obsolete" have dropped out of the language in the competition of synonyms, others survived with a meaning more or less different from the original one. This process is called synonymic differentiation and is so current that is regarded as an inherent law of language development.
The development of the synonymic group land has been studied by A.A. Ufimtseva. When in the 13 century soil was borrowed from French into English its meaning was "a strip of land".
OE synonyms eorpe, land, folde ment "the upper layer of earth in which plants grow".
Now, if two words coincide in meaning and use, the tendency is for one of them to drop out of the language.
Folde became identical to eorpe and in the fight for survival the letter won. The polysemantic word land underwent an intense semantic development in a different direction and so dropped out of this synonymic series.
It was natural for soil to fill this lexical gap and become the main name for the notion "the mould in which plants grow". The noun earth retained this meaning throughout its history whereas the word ground, in which this meaning was formerly absent, developed it. As a result this synonymic group comprises at present soil, earth, ground.
The assimilation of synonyms consists in parallel development. This law was discovered and described by G. Stern,, H.A. Treble and G.H. Vallins in their book "An ABC of English Usage", Oxford, 1957, p. 173 give as examples the pejorative meanings acquired by the nouns wench, knave and churl which originally ment "girl", "boy", and "labourer" respectively, and point out that this loss of old dignity became linguistically possible because there were so many synonymous words of similar meaning. As the result all the three words underwent degradation in their meanings:
wench - indecent girl knave - rascal churl - country man.