Epilogue:

Well, that was over quickly! It was all a blur of posting, editing, and reposting, but from what I could tell, @El-Guest had solved 8 out of the 10 at the same time that @geekahedron was working out how to post his complete solution. It seems that @geekahedron solved all 10 on his own. While technically @El-Guest may have posted the assembled solution first, I'm sure he would be understanding if I credit the answer to the new guy.

Here are more fun facts about these words:

In the example, LINES is also contained in UGLINESS (but UG_____S would have been too easy to recognize)

4. TINY is also contained in SCRUTINY

5. ROSE is also contained in PROSECUTE, MICROSECOND, HETEROSEXUAL, and PROSELYTIZE

8. GNAT is also contained in SIGNATURE

9. DIME is also contained in IMPEDIMENT

Epilogue:

Well, that was over quickly! It was all a blur of posting, editing, and reposting, but from what I could tell, @El-Guest had solved 8 out of the 10 at the same time that @geekahedron was working out how to post his complete solution. It seems that @geekahedron solved all 10 on his own. While technically @El-Guest may have posted the assembled solution first, I'm sure he would be understanding if I credit the answer to the new guy.

Here are more fun facts about these words:

In the example, LINES is also contained in UGLINESS (but UG_____S would have been too easy to recognize)

4. TINY is also contained in SCRUTINY

5. ROSE is also contained in PROSECUTE, MICROSECOND, HETEROSEXUAL, and PROSELYTIZE

8. GNAT is also contained in SIGNATURE

9. DIME is also contained in IMPEDIMENT

Became Hot Network Question
1

And now you see it II (the B side)

It amuses me that the word CANOES has been there in VOLCANOES all along. And URCHIN is barely hiding in the word LURCHING. And ASPIRIN is right there in ASPIRING. SISTER is in RESISTER. AKIN is in TAKING. HANGERS is in EXCHANGERS. And DEVELOPING has always been thinking about ELOPING.

These words have always been there. Although I've been looking at them my whole life, I've only just noticed them recently. They were hidden in plain sight!

Maybe you've noticed them before. Let's test your powers of observation on some others.

Example:

Fill in the blanks below with a well-known 5-letter word to complete all the words:
HO_____S
INC_____
REC_____

--------------------------------------

because it completes all the words:

HOLINESS
INCLINES
RECLINES


See how many of the 10 below you can solve.

Super helpful clue: The fill-in word is semantically and etymologically unrelated to the containing words. (Well, almost always.)

1.  Fill in the blanks below with a well-known 4-letter word to complete all the words:
MAN____
FOR____
DIN____

2.  Fill in the blanks below with a well-known 4-letter word to complete all the words:
MA____G
BA____G
TA____G

3.  Fill in the blanks below with a well-known 6-letter word to complete all the words:
P______
FI______
SHO______

4.  Fill in the blanks below with a well-known 4-letter word to complete all the words:
SA____
MU____
DES____

5.  Fill in the blanks below with a well-known 4-letter word to complete all the words:
P____
MO____
KE____NE

6.  Fill in the blanks below with a well-known 6-letter word to complete all the words:
P______G
B______G
______G

7.  Fill in the blanks below with a well-known 6-letter word to complete all the words:
AC______G
SE______G
EX______G

8.  Fill in the blanks below with a well-known 4-letter word to complete all the words:
CO____E
MA____E
STA____E

9.  Fill in the blanks below with a well-known 4-letter word to complete all the words:
SE____NT
RU____NT
CON____NT

10.  Fill in the blanks below with a well-known 4-letter word to complete all the words:
LEF____G
RIGH____G
BA____GS


If you missed the A side, here it is.