Is it possible to show the node term in a block title using rep[lacement]tags?

Block titles are normally not passed though input filters, so probably not. (I think)

Your quickest method may be to make a custom block-block-n.tpl.php and render/change your custom title there. Needs PHP.

Hi,

thank you for you help.

I'm not very good in php. I will try to ask it on the forum.

thank you again.