Gabriel,

> But besides the grammar does the Saddaniti, Suttamala say
> something about the meaning of the root “Buddh”?

The root is "budh", not "buddh".

> As I posted before the article that I found mention three
> meanings for “Buddha”:

1-to know, understand (avagamana)

2-Awake or destruction of the sleep state (niddakkhaya,)

3-open or blossom (vikasana)

==============
Jim: I have checked the Dhaatumaalaa of the Saddaniiti (Smtih's ed.).

It has the following four entries for the root "budh":

517 budha bodhane
1132 budha avagamane
1133 budha bodhane
1206 budhi hi.msaaya.m (to injure, harm)

We can disregard the last one as it is the root for the verb "bundheti" and
the noun "palibodho" and has nothing to do with the noun "buddha". In the
entry for 1132, the Saddaniiti glosses "avagamana.m" with "jaanana.m"
(knowing) and in 1133, "bodhane" is explained as including the following:
budha ~naa.ne, budha vikasane, budha niddakkhaye. So your no. 2 and 3 belong
under "budha bodhane". For studying the traditional explanation of the word
"buddha", the Khuddakapaa.tha commentarial passage fhat Nina quoted from, in
part, is a good place to start. But I do find it and the Pali text difficult
to follow and grasp. Reading the translation probably won't be enough for
the serious student. One has to delve into it deep and devote many hours of
further study for a better understanding. And have the resources at hand to
work with.

Best wishes,
Jim