-Dumbre an Uncommon Suffix

From the mailbox:

I have found six words with the ending -dumbre: servidumbre, muchedumbre, mansedumbre, incertedumbre, dertedumbre, podredumbre. Where can I find the meaning of this ending -dumbre as it is not in any reference books I have?

As it turns out, there are around a couple dozen words with the suffix -dumbre. -Dumbre is a not-so-common suffix that means something like the English "-ness" or "-tude." In other words, it's a suffix that makes a noun referring the quality of the adjective to which the suffix is attached. Examples should make this clearer; among the the -dumbre words, none of them particularly common, are mansedumbre (calmness), servidumbre (servitude or a servant), podredumbre (rottenness or corruption), pesadumbre (sorrow), dulcedumbre (sweetness) and certedumbre (certitude or certainty). Perhaps the most common of such words is muchedumbre, which refers to a great number or, if the context suggests, a crowd or multitude.

Note that nouns ending in -dumbre are typically feminine, much like those ending in -tud.