Abbreviation of Système international. (Système international d'unités) (the international standard metric system)

(music) si, the note 'B'

if, whether / if (assuming that) / even if / although, while

so, such (intensifier) / however (to whatever extent or degree)

Si bavard qu'il soit, il ne dit rien de stupide.
However talkative he may be, he doesn't say anything stupid.; however (to whatever extent or degree) / however (to whatever extent or degree)

Si bavard qu'il soit, il ne dit rien de stupide.
However talkative he may be, he doesn't say anything stupid.; Si bavard qu'il soit, il ne dit rien de stupide. / however (to whatever extent or degree)

Si bavard qu'il soit, il ne dit rien de stupide.
However talkative he may be, he doesn't say anything stupid.; However talkative he may be, he doesn't say anything stupid.

yes (used to contradict a negative statement)

(mathematics, logic) if and only if (implies and is implied by)

if possible

unless

if need be, if necessary

B major