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8.12: Sometimes the Two Prefixes In- Assimilate

Difficulty Level: At Grade Created by: CK-12
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Sometimes the Two Prefixes In- Assimilate

1. When either of the two prefixes in- is added to certain stems, the <n> will assimilate and become the same as the first letter of the stem. In all of the following words, the first two letters are some form of one of the in- prefixes. Sometimes the <n> remains <n>, and sometimes it assimilates. Analyze each word into its prefix and stem, showing any changes due to assimilation:

Word = Prefix + Stem
immediate = i\begin{align*}\cancel{n}\end{align*} + m + mediate
individual = in + dividual
inform = in + form
irregular = i\begin{align*}\cancel{n}\end{align*} + r + regular
illustrate = i\begin{align*}\cancel{n}\end{align*} + l + lustrate
invested = in + vested
illusion = i\begin{align*}\cancel{n}\end{align*} + l + lusion
immense = i\begin{align*}\cancel{n}\end{align*} + m + mense

2. Sort the words into these groups:

Words in which <n> . . .
changed to <m> changed to <r> changed to <l> did not change
immediate irregular illustrate individual
immense illusion inform

3. So far the prefixes in- behave like the prefixes ad- and sub-: Sometimes they are simply added to the stem with no changes in spelling, and sometimes they assimilate so that the last letter of the prefix is the same as the first letter of the stem.

But in some words the <n> in in- changes to an <m> even though the first letter of the stem is not an <m>! For instance: i\begin{align*}\cancel{n}\end{align*} +m + press = impress. This change from <n> to <m> - and from [n] to [m] — still makes the word easier to say. It is called partial assimilation.

4. All of the following words contain one of the prefixes in-. In some words the <n> has assimilated partially by changing to an <m> in front of stems that don't start with [m] or <m>. In some words the <n> has not assimilated at all. Analyze each word to show what happened when in- was added to the stem in that word:

Word = Prefix + Stem
impress = i\begin{align*}\cancel{n}\end{align*} + m + press
inquire = in + quire
improve = i\begin{align*}\cancel{n}\end{align*} + m + prove
insufficient = in + sufficient
important = i\begin{align*}\cancel{n}\end{align*} + m + portant
indicted = in + dicted
imbalance = i\begin{align*}\cancel{n}\end{align*} + m + balance
impossible = i\begin{align*}\cancel{n}\end{align*} + m + possible

5. The five words in which the <n> changed to <m> are . . .

\begin{align*}& impress && important && impossible\\ & improve && imbalance\end{align*}

6. Sometimes the <n> in the prefixes in- assimilates partially to <m> before stems that start with the letters \begin{align*}\underline{<b>}\end{align*} and \begin{align*}\underline{<p>}\end{align*}.

Teaching Notes.

Item 1. The word balance comes from Latin bilanx(bi “two” + lanx “plate”) - as in the two plates, or pans, in a balance scale.

Item 3. The assimilation of [n] to [m] before [b] and [p] makes pronunciation easier because the mouth has to move less to get from [m] to [b] or [p] than it does to get to [b] or [p] from [n]. The sounds [m], [b], and [p] are all pronounced with the lips together and the tongue in the same position ; the sound [n] is pronounced with the tip of the tongue pushed against the back of the upper dental ridge. This process of partial assimilation continues. For instance, the word input is probably pronounced more often with [m] rather than [n], and Webster's Third International lists imput as a variant of input. Partial assimilation is also behind the tendency of people to pronounce hypnotize with [m] rather than [n] and the more rare tendency of youngsters to pronounce chimney with [bl] rather than [n].

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