Today's wotd was expunge, but in the course of my cursory analysis, I got sidetracked by obliterate, which led me to what the real wotd should have been--perplexed. I'm not anywhere near OED, making this distinction more difficult, since in my gut, I think DD is yet again wrong, or at least incomplete and therefore, misleading. So, I'll start with the word that starts to bring this trilogy into focus:
Efface comes from the Latin for "out" "appearance", or to take out of appearance, which then evolved into "to rub out" [no, not to kill]. The physical act of rubbing was important, as if one rubs one's face to change it's appearance (i.e., get rid of sleep, make up) for tangibles (efface the spot from the carpet, efface the bubble on the SAT), but now has the connotation of the effect without the rubbing for intangibles (efface the memory of taking the Bar exam with lots of alcohol) and with intangibles, seems to be limited solely to the idiom of memory, knowledge or history, history being an effect of memory in some sense (efface useless knowledge, efface the culture of China before socialism). But now, it's also more than just rubbing, but the repetitive motion. Sandblasting effaced the gum from the sidewalk. The tides effaced the beach, as well as the sandcastle. Poor control of tourism and their touching of the engravings, effaced the fine details. Acid rain has effaced the carvings from many ancient Greek buildings. So, it's the physical act of rubbing or repetitive touching akin to rubbing tangible things out of existence, and rubbing out memory or memory-like things.
Expunge comes from the Latin for "to prick", as apparently it was used as an indicia that something on a list needed to be omitted. The black mark that we hear may be beside someone's name now means that this person gets left off the list, but according to DD, in current usage, it has some vague meaning of "to erase or strike out". However, in reality, it is only ever used to with removing things from records (whether legal or otherwise), the new list. Expunge his record of the DUI. Expunge her record of misidentification with the high school brawl. Expunge the minutes of the discussion about corporate expansion. Not expunge antiquated technology from the office. Nor expunge creativity from education.
And finally, obliterate, from the Latin for "to write over letters" or alternatively, "to forget". Of course, it is only used with tangible and intangible categories (no matter how much we want to, we don't obliterate our mothers-in-law or obliterate witnesses; we try to diminish influence and kill, irrespectively), and obliterate can be accomplished in a single or less than repetitive blow. The bomb obliterated all trace of the church. The Taliban's mission was to obliterate other religious symbols. The problem with obliterate, unlike efface and expunge, is that obliterate intends to remove all reference, knowledge, or existence of the thing, leaving nothing behind to remind, but if one is really effective at such obliteration, there would be no proof that the thing existed to prove that it had been obliterated. You could imagine the philosophical tautology of trying to explain that you had obliterated something but not being able to say what you had obliterated because to do so would be to bring it back into existence. Efface doesn't have that problem since it is a physical thing which still may be in memory (I remember where the lines on Washington's face on the quarter were before they were effaced by years of use) or not in memory but still in physical record (despite my attempts to efface my memory of studying for the bar, I still retain my bar notes as a good reference). And expunge is similar to effacing the physical form since there may still be memory of the alleged offense, charge or claim.
Ed. note. I still would probably never use efface, I already use expunge, in it appropriate legal context, and I prefer obliterate because it is so much more evocative.