I'm sorry, but my research indicates
that the Celts who first drew knotwork patterns had no
such meaning attached to their work.
Now, there have been hundreds of years since knotwork
patterns were first invented. It's not impossible that
meanings have been attached to certain patterns over
time. From what I can tell, such meanings do exist, but
as far as I know, they are very localized and
relatively recent in origin.
Addendum: documented meanings I've found.
In Brigit's Feast (Vol. 2 No. 1, pp. 9, 11)
Frank Mills writes...
The interlaced patterns with their unbroken lines symbolize
humankind's pilgrimage, both as a quest to return to our divine
source and our spiritual growth as we move along in the quest.
The pattern is to be mentally unraveled, which, while occupying
the mind with a repetitive task, creates a deeper concentration
enabling us "to see." In this it is akin to the use of a mantra
or rosary beads.
...though in a footnote he says....
It must be remembered that in our interpretation of Celtic
art we cannot know the mind of the ancient Celts who developed
these forms, thus the best we can do is to hopefully 'read
between the lines' correctly and make some educated guesses.