Back Formation is the method of forming new words by subtracting something from old ones. The adverbs sideling, groveling, darkling were formed by adding the suffix -ling. But in such sentences, he walks sideling, he lies groveling, I listen darkling, the suffix -ling looked exactly like the ending -ing with the oust that the verbs to sidle, to grovel, to darkle were formed from the adverbs by the subtraction of -ing. But the ending which is often subtracted is -y. The noun greed, the verb laze, cose and jeopard are formed by the subtraction of -y. The words difficult, pup, cad are obtained from difficulty, puppy, and caddy through back formation.
Many new words have been formed by subtracting -er, -ar, -or like Harbinger – Harbing, hawker – hawk, burglar – burgle, beggar – beg.
The words to housekeep, to dressmake, to henpeck and to sunburn have come to us through the process of back-formation from housekeeper, dressmaker, henpecked and sunburnt.