-ly


The suffix -ly in English is usually a contraction of -like, similar to the Anglo-Saxon lice and German lich. It is commonly added to an adjective to form an adverb, but in some cases it is used to form an adjective, such as ugly or manly. The adjective to which the suffix is added may have been lost from the language, as in the case of early, in which the Anglo-Saxon word aer only survives in the poetic usage ere.
Though the origin of the suffix is Germanic, it may now be added to adjectives of Latin origin, as in publicly.
When the suffix is added to a word ending in y, the y changes to an i before the suffix, as in happily. This does not always apply in the case of monosyllabic words; for example, shy becomes shyly.
When the suffix is added to a word ending in double l, no additional l is added; for example, full becomes fully. Note also wholly, which may be pronounced either with a single l sound or with a doubled l. When the suffix is added to a word ending in a consonant followed by le, generally the e is dropped, the l loses its syllabic nature, and no additional l is added; this category is mostly composed of adverbs that end in -ably or -ibly, but it also includes other words such as nobly, feebly, triply, and idly. However, there are a few words where this contraction is not always applied, such as brittlely.
When -ly is added to an adjective ending -ic, the adjective is usually first expanded by the addition of -al. For example, there are adjectives historic and historical, but the only adverb is historically. There are a few exceptions such as publicly.
Adjectives in -ly can form inflected comparative and superlative forms, but most adverbs with this ending do not. For more details see Adverbs and Comparison in the English grammar article.