The -er at the end of the word ...... Is a suffix and the word...... Has been formed by deleting that suffix.
However, the-y at the end of lazy and, similarly, the -ar the end burglar are not suffixes; they are part of the spelling of the root.
The the word laze and similarly the word burgle have been formed by deleting that past of the root which is not a suffix but which is likely to have been formed by deleting that part of the root which is not a suffix but which is likely to have been mistaken for a suffix on the basis of a false analogy.
Irrespective of whether words of this type are formed by deleting a suffix or by deleting what erroneously looks like a suffix, deleting the terminal part of the base is an obligatory feature of this type of word-formation.
This process of deletion makes back-formation more or less the opposite of derivation.
In all case of back-formation, a suffix or what looks like a suffix is deleted from the word which is used as the base for back-formation.
Some linguists(...merchand) , therefore, hold the viwe that, for word-formation of this type, back-derivation is a more appropriate term than back-formation.