labia refers to the vaginal lips, not the pubic area in general
Being equipped with a labia myself, I AM familiar with what the labia is or isn't. :)
To get /technical/ about it, there is no such thing as a labia. There's the Labia majora, commonly refered to as the 'outer lips' Every woman actually has two of these, one on each side. post #94155 has a large Labia majora.
The Labia minora are commonly refered to as 'inner lips' or 'inner folds' You can see them prominantly in post #89101 and #75760, as well as a number of other posts.
Of the two, you're more likely to hear the outer lips and the entire vulval area referred to as 'labia'.
In any regard, the labia majora and labia minora both vary hugely from person to person. Some people have very small labia majora (REAL PERSON PICTURE: http://commons.wikimedia.org/wiki/File:Human_vulva.jpg has a very small labia majora and prominant labia minora) while others have larger labia majora that conceal the labia minora (as such: http://upload.wikimedia.org/wikipedia/commons/2/29/03_Genitalien.jpg ) and others are 'mid way' (http://upload.wikimedia.org/wikipedia/commons/2/2e/Female_external_genitalia.jpg http://commons.wikimedia.org/wiki/File:A_vulva.jpeg )
So.. /idealy/ the tags would be something like "fat pussy lips" or "large pussy lips" or "large outer lips" and "large inner lips", but right now, we've got 'plump labia' which has a great many labia that are not plump, and, near as *I* can tell, no lag for prominant/visible labia minora.
Also, throw a kink in things further, there's also a 'fat_labia' tag that seems to mostly be used for nezumi's works, as well as a few pictures that involve larger labia majora.