This little epithet is a favourite of mine. It has such mixed overtones, and its actual use embodies those contrasts: a slangy, casual clipping of a formal term, used by the confident, vaguely slumming elite to refer to something that is as beneath them as the term sounds like it is.
Let’s start with the echoes. Infra probably makes you think of infra-red (actually properly spelled infrared as one word, but for years in my youth I thought that this rhymed with impaired and did not connect it with the light of longer wavelength than red). Dig is what you do to go further into the ground, but it can also be what you do to something that’s groovy. I think infra dig sounds like the name of some late-’60s psychedelic music group, pumping out singles you can frug to.
But what it actually is is a clipping of infra dignitatem, Latin, ‘below dignity’. It belongs to that set of loose Latin usages characteristic of the rich educated set – the sort of toffee-nosed idle rich nobility who bounded around in the Edwardian era wearing whites during the day and always dressing for dinner. People of untold riches and status who always managed to have nicknames such as Binky and Chirps. Imagine P.G. Wodehouse. Or, better, think of any of several movies or series featuring Maggie Smith. You can just hear it: “Oh, but don’t you think that’s rather infra dig, dear?” You wouldn’t want to do something that would dig below you – which is to say undermine you – would you?
This is a term, then, that really speaks mainly of its user. The person speaking it is presenting himself or herself as familiar with Latin to the point of casualness, and not really pedantic about it – a person to whom things come easily, a person who is used to trailing off intonations in a croaky drawl, a person who is not accustomed to questioning his or her superiority. Perhaps these days toffs don’t use it so much; I don’t know. But at least some members of the intellectual elite do: the well-educated, erudite, learnèd and not ashamed to let it be known.
So of course I use this term. I may not be idle rich, but you will seldom find a person more secure in his self-location in the intellectual empyrean. What do I use it in reference to? Rhyming dictionaries, mainly. And anagram finders. To my mind, such things are as utterly infra dig as training wheels on a bicycle. Never mind the old toff idea that associating with the “lower classes” is infra dig. I don’t care about proving I’m rich or high-class – indeed, scorning people on the basis of income is quite beneath me (and not just because I’m not rich). But I simply don’t want to act like someone who, you know, needs help with words. You dig?