Blending, or contamination, is the name of the process which occurs when at least two lexemes are shortened and joined together disregarding their initial boundaries. What is created in such a process can be called a blend, though other names are also found to operate — those being portmanteau or telescoped words.
A characteristic feature of contamination, and also the one that enables a speaker to coin blends freely is that the semantic content of the derivative most of the time carries some of the meaning of its constituents. There are few rules that govern blend-creation. The speaker is not restricted in any way from using part of any length of either of the constituents (the obvious cases would be the ability to pronounce such a word), thus distinguishing elements that add up to the derivative is not always an easy task. This leads to a conclusion that blends found in English are constructed according to various patterns.
Among others, one can find words that are constructed of two constituents, but only one of them is shortened, or even the two overlap each other:
|Lexeme 1||Lexeme 2||Blend|