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9.12: More About the Prefix Ex-

Difficulty Level: At Grade Created by: CK-12
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More About the Prefix Ex-

1. In the words you have worked with so far the prefix ex- has always been spelled <ex>. But when ex- is added to a stem that starts with an <f>, the <x> assimilates to an <f>. In many other words the <x> is deleted and nothing is put in its place. This partial assimilation makes pronunciation easier.

Each of the following words begins with some form of the prefix ex-. Analyze each one into its prefix and stem. Show any assimilations that take place:

Word = Prefix + Stem
exclaiming = +
effective = +
editor = +
exhibited = +
elaborate = +
emerging = +
emotional = +
evidently = +
efficient = +
elections = +
enormous = +
excitement = +

2. Usually ex- assimilates only partially, by just deleting the <x>. It often does so with stems with which other prefixes assimilate fully to make a double consonant. So though we have elect with a single <l>, we have collect with <ll> because of full assimilation:

elect = e\begin{align*}\cancel{x}\end{align*}x + lect, with <l>

collect = co\begin{align*}\cancel{m}\end{align*}m + l + lect, with <ll>.

Here are some other pairs like elect and collect. In each pair the first word contains an assimilated form of the prefix ex-. The second word contains a different prefix. Both words in each pair contain the same stem. Analyze each word into its prefix plus stem. Then underline any double consonants:

Word = Prefix + Stem
election = e\begin{align*}\cancel{x}\end{align*}x + lection
collection = co\begin{align*}\cancel{m}\end{align*}m + l + lection
emotion = +
commotion = +
immigrate = +
edicts = +
addicts = +
eminent = +
imminent = +
erected = +
corrected = +
elapsed = +
collapsed = +
edition = +
addition = +
eroding = +
corroding = +

3. Usually when ex- is added to a stem that starts with \begin{align*}<\mathrm{s}>\end{align*}<s>, an unusual assimilation takes place. For example, in the word expect the base is actually spect, the same base that is in inspect and respect. But in expect the \begin{align*}<\mathrm{s}>\end{align*}<s> is deleted: ex + \begin{align*}\cancel{s}\end{align*}spect. All of the following words have this same unusual assimilation. Analyze each one into prefix plus stem, showing the \begin{align*}<\mathrm{s}>\end{align*}<s>-deletion:

Word = Prefix + Stem
expect = ex + \begin{align*}\cancel{s}\end{align*}spect
exist = ex + \begin{align*}\cancel{s}\end{align*}sist
expire = ex + \begin{align*}\cancel{s}\end{align*}spire
executive = ex + \begin{align*}\cancel{s}\end{align*}secutive
exertion = ex + \begin{align*}\cancel{s}\end{align*}sertion
extinct = ex + \begin{align*}\cancel{s}\end{align*}stinct
extant = ex + \begin{align*}\cancel{s}\end{align*}stant
extinguisher = ex + \begin{align*}\cancel{s}\end{align*}stinguisher
exude = ex + \begin{align*}\cancel{s}\end{align*}sude

Teaching Notes.

Ex- has a complex pattern of assimilation. A reasonable summary could go as follows:(i) In older words ex- assimilates fully to ef- before <f>; (ii) it remains ex- before all other voiceless consonants and before vowels; (iii) it assimilates partially to e- before voiced consonants; (iv) before stems that start with \begin{align*}<\mathrm{s}>\end{align*}<s> it remains ex- but the initial \begin{align*}<\mathrm{s}>\end{align*}<s> in the stem is deleted. There are further complications, usually in exotic or technical words, but the following are worth noting:

\begin{align*}\text{eccentric} & = \text{e}\cancel{\text{x}} + \text{c} + \text{centric} && \text{eczema} = \text{e} \cancel{\text{x}} + \text{c} + \text{zema} \\ \text{ecclesiastic} & = \text{e} \cancel{\text{x}} + \text{c} + \text{clesiastic} && \text{escape} = \text{e} \cancel{\text{x}} + \text{s} + \text{cape} \\ \acute{\text{e}}\text{clair} & = \text{e} \cancel{\text{x}} + \text{clair} && \text{escort} = \text{e} \cancel{\text{x}} + \text{s} + \text{cort} \\ \text{eclipse} & = \text{e} \cancel{\text{x}} + \text{c} + \text{lipse} && \text{espresso} = \text{e} \cancel{\text{x}} + \text{s} + \text{presso} \\ \text{ecstasy} & = \text{e} \cancel{\text{x}} + \text{c} + \text{stasy} && \text{essay} = \text{e} \cancel{\text{x}} + \text{s} + \text{say} \end{align*}

The deletion of \begin{align*} <\mathrm{s}> \end{align*} at the beginning of stems is not as whimsical as it may seem: Since the <x> spells the combination [ks], the \begin{align*} <\mathrm{s}> \end{align*} is no longer needed to spell the [s] sound. For more on ex- and its assimilations, see AES, pp. 181-83.

Item 2. The point being made here is worth some emphasis since it is not at all unusual for ex- words like those listed here to be mispelled with double consonants after the <e>.

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Date Created:
Feb 23, 2012
Last Modified:
Jul 07, 2015
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