in-¹ or il- or im- or ir-
pref.
Not: inarticulate. Before l, in- is usually assimilated to il-; before r to ir-; and before b, m, and p to im-. See Usage Note at un-¹.

[Middle English, from Old French, from Latin.]

in-² or il- or im- or ir-
pref.

1. In; into; within: inundation. Before l, in- is usually assimilated to il-; before r to ir-; and before b, m, and p to im-.
2. Variant of en-¹.

[Middle English, from Old English (from in, in; see in¹) and from Old French (from Latin , from in, in, within).]

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The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.

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