Technique
Portmanteau
Carroll coined the term in Through the Looking-Glass (1871). The portmanteau is now a recognised word-formation process; James Joyce used it extensively in Finnegans Wake.
Definition
A word formed by fusing two or more words, blending their sounds and meanings into a single new coinage.
Example
Lewis Carroll: 'slithy' (lithe + slimy); 'chortle' (chuckle + snort); 'mimsy' (miserable + flimsy).