In linguistic morphology, the term bracketing paradox refers to morphologically complex words which apparently have more than one incompatible analysis, or bracketing, simultaneously.

One type of a bracketing paradox found in English is exemplified by words like unhappier or uneasier.[1] The synthetic comparative suffix -er generally occurs with monosyllabic adjectives and a small class of disyllabic adjectives with the primary (and only) stress on the first syllable. Other adjectives take the analytic comparative more. Thus, we have older and grumpier, but more correct and more restrictive. This suggests that a word like uneasier must be formed by combining the suffix er with the adjective easy, since uneasy is a three syllable word:

$\Big[\mbox{un-}\Big] \Big[ \big[\mbox{easi}\big] \big[\mbox{-er}\big] \Big]$

However, uneasier means "more uneasy", not "more difficult". Thus, from a semantic perspective, uneasier must be a combination of er with the adjective uneasy:

$\Big [ \big[\mbox{un-}\big] \big[\mbox{easi}\big] \Big ] \Big[\mbox{-er}\Big]$

however violates the morphophonological rules for the suffix -er. Phenomena such as this have been argued to represent a mismatch between different levels of grammatical structure.[2]

Another type of English bracketing paradox is found in compound words that are a name for a professional of a particular discipline, preceded by a modifier that narrows that discipline: nuclear physicist, historical linguist, political scientist, etc.[3][4] Taking nuclear physicist as an example, we see that there are at least two reasonable ways that the compound word can be bracketed (ignoring the fact that nuclear itself is morphologically complex):

1. $\Big [ \mbox{nuclear} \Big ] \Big [ \big [ \mbox{physic(s)} \big ] \big [\mbox{-ist} \big ] \Big ]$ - one who studies physics, and who happens also to be nuclear
2. $\Big[ \big [\mbox{nuclear} \big] \big [\mbox{physic(s)} \big] \Big] \Big [\mbox{-ist} \Big]$ - one who studies nuclear physics, a subfield of physics that deals with nuclear phenomena

What is interesting to many morphologists about this type of bracketing paradox in English is that the correct bracketing 2 (correct in the sense that this is the way that a native speaker would understand it) does not follow the usual bracketing pattern 1 typical for most compound words in English.