/ ɪnˈsɜːʃn; NAmE ɪnˈsɜːrʃn/ noun
1.
[ U , C ] insertion (in / into sth) the act of putting sth inside sth else; a thing that is put inside sth else :
An examination is carried out before the insertion of the tube.
2.
[ C , U ] a thing that is added to a book, piece of writing, etc.; the act of adding sth :
the insertion of an extra paragraph
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WORD ORIGIN
mid 16th cent. (in sense 2): from late Latin insertio(n-) , from Latin inserere , from in- into + serere to join.