What are the implicit rules for creating new portmanteaux in English?

Question

Wikipedia defines a portmanteau¹ as:

“Portmanteau word” is used to describe a linguistic blend, namely “a word formed by blending sounds from two or more distinct words and combining their meanings.”

Wikepedia further provides a list of common English portmanteaux, such gaydar, guyliner, liger, tigon, turducken, queef, Oxbridge, Spanglish, and even Wikipedia itself.

There seem of to be some sort of implicit rules operative here which are quite regular in some ineffable way, but I cannot quite work out what those are, because I think I see several different, potentially conflicting patterns at work.

My question is:

• What is the internalized rule or rules that native English speakers seem to automatically use to create these?

For extra credit, albeit perhaps pertaining more to the Linguistics SE:

• Are these implicit rules unique to English, or are they fairly constant across other languages in which such blends occur?

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1. Which the French would call a mot-valise and the Germans a Kofferwort.

Answer 1

I can only speak from an English perspective, but the two most important aspects that come to mind for any portmanteau are pronounceability and ease of understanding (there are a number of other characteristics that only apply to specific kinds).

Spanglish is a good example. For pronunciation, you probably wouldn't use something like Spaniglish or Enganish because they just don't sound as good. In a similar sense, Spanglish gives a fairly obvious sense of its source words, Spanish and English, whereas these other variants are less clear. Then there's the added bonus of the "n" being shared by both, the root of "English" in "Anglish" (as in Anglican, Anglo-Saxon), even the implication of "star-spangled banner" and the ideas of American patriotism vs. immigrant culture, you could go on and on.

The only other caveat I can think of is with cross-breeding, so liger vs. tigon, plumcot vs. pluot vs. aprium, etc. There are specific rules (see here and here for example); for animals it's generally which parent belongs to which species (male vs. female), and with hybrid fruits and such it has to do mostly with how much of one type or the other is contained in the grafted specimen.