Define Significant Other

I do believe it means your better half

I do believe Eva has it right. Your better half, a person you care deeply for, love or adore.

And now it's my time to be technical!

sig·nif·i·cant [sig níffik?nt]
adj
1.  meaningful: having or expressing a meaning 
2.  communicating secret meaning: having a hidden or implied meaning
a significant nod of the head
 
3.  momentous and influential: having a major or important effect
a significant idea
 
4.  substantial: relatively large in amount
Her work was a significant contribution to the project.
 
5.  statistics occurring not merely by chance: relating to the occurrence of events or outcomes that are too closely linked statistically to be mere chance 

Just add the word "other". : D

-Ki- 

Isn't it funny how we can get hung up on lables?  A significant other is the person you are presently sharing your life with, whether it's a spouse, a live-in partner or just a girl/boy friend.

Try to let go of the labels and just live your life.  Follow your gut, it is seldom wrong.

All the best,

gg