There are many cases of similarity between words easily confused with synonymy but in fact essentially different from it.
Lexical variants, for instance, are examples of free variation in language, in so far as they are not conditioned by contextual environment but are optional with the individual speaker. E. g. northward / norward; whoever / whosoever. The variation can concern morphological or phonological features or it may be limited to spelling. Compare weazen/weazened ‘shrivelled and dried in appearance’, an adjective used about a person’s face and looks; directly which may be pronounced [di'rektli] or [dai'rektli] and whisky with its spelling variant whiskey. Lexical variants are different from synonyms, because they are characterised by similarity in phonetical or spelling form and identity of both meaning and distribution.
The cases of identity of stems, a similarity of form, and meaning combined with a difference in distribution should be classed as synonyms and not as lexical variants. They are discussed in many books dedicated to correct English usage. These are words belonging to the same part of speech, containing identical stems and synonymical affixes, and yet not permitting free variation, not optional. They seem to provoke mistakes even with native speakers. A few examples will suffice to illustrate the point. The adjectives luxurious and luxuriant are synonymous when meaning ‘characterised by luxury’. Otherwise, luxuriant is restricted to the expression of abundance (used about hair, leaves, flowers). Luxurious is the adjective expressing human luxury and indulgence (used about tastes, habits, food, mansions). Economic and economical are interchangeable under certain conditions, more often, however, economic is a technical term associated with economics (an economic agreement). The second word, i.e. economical, is an everyday word associated with economy; e. g. economical stove, economical method, be economical of one’s money.
Synonyms of this type should not be confused with paronyms, i.e. words that are kindred in origin, sound form and meaning and therefore liable to be mixed but in fact different in meaning and usage and therefore only mistakenly interchanged.
The term paronym comes from the Greek para ‘beside’ and onoma ‘name’, it enters the lexicological terminology very conveniently alongside such terms as synonyms, antonyms, homonyms and allonyms.1
Different authors suggest various definitions. Some define paronyms as words of the same root, others as words having the same sound form, thus equalising them with word-families or homonyms. Any definition, however, is valuable only insofar as it serves to reflect the particular conception or theory of the subject one studies and proves useful for the practical aims of its study. As the present book is intended for the future teachers of English, it is vital to pay attention to grouping of words according to the difficulties they might present to the student. That is why we take the definition given above stressing not only the phonetic and semantic similarity but also the possible mistakes in the use
of these “hard words”. This is the case with the adjectives ingenious and ingenuous. The first of these means ‘clever’ and may be used both of man and of his inventions and doings, e. g. an ingenious craftsman, an ingenious device. Ingenuous means ‘frank’, ‘artless’, as an ingenuous smile.
The likeness may be accidental as in the verbs affect and effect. The first means ‘influence’, the second — ‘to produce’. These come from different Latin verbs. The similarity may be also due to a common source. It is etymologically justified in alternate ‘succeeding each other’ and alternative ‘providing a choice’, or consequent ‘resulting’ and consequential ‘important’, or continuance ‘an uninterrupted succession’ and continuation which has two distinct meanings ‘beginning again’ and ‘sequel’ as the continuation of a novel.