You could change:
.MatchWholeWord = True
to:
.MatchWholeWord = False
but this might have quite undesirable effects. For example, if the found word also forms part of longer, unrelated, words, those might get updated too. You might get better results inserting:
.MatchAllWordforms = True
after:


.Replacement.ClearFormatting
but that, too can have undesirable results. Test both on a document, with:
.Replacement.Highlight = True
inserted after:
.Replacement.ClearFormatting
and set your preferred highlight colour before running the macro. If you don't get the desired results, you'll need to insert an additional F/R expression for each plural.

__________________
Cheers,
Paul Edstein
[Fmr MS MVP - Word]

Hi paul,

as suggested by you, I have tried incorporating the new code. Clearly, MatchWholeWord=False doesn't give desired results.

Moving on to .MatchAllWordForms=True, in spite of all types of changes in my test file, database or even some lines of code, it gives a run-time error code 5610, stating that "the find what text for find all word forms can search only alphabetic letters".

My test file has following line, "The school technical library issues Mathematics, Physics and chemistry books to the students and teachers".

The database has following words to be replaced with :-
School to Sch, Library to lib, Technical to Tech, Mathematics to Maths, Physics to Phy, Chemistry to Chem, student to stdnt and teachers to tchr.

The required result must be "The sch tech lib issues Maths, Phy and chem books to the stdnts and tchrs"

I have read online that this function only works with english language and that it wont work along with .MatchWholeWord=True or .MatchCase=True. But even including these changes has not helped.