Generally, literacy is used nowadays to convey an exceeding familiarity or comfort beyond a fluency with a given language or idea or set of skills. Its meaning gets at the core of what it means to know and to do and to be, how skills are imparted and articulated, how information is shared and organized, all of these objective tasks require ‘literacy’ to be at the top of the game.
This is one of those circular words that is defined be the state of being pretty much what it is, so if you look up ‘literacy’, you’ll often find that it means being ‘literate’. Yet how can this mode of definition ever really get at explaining what something is to the uninitiated, let alone the curious?
Literacy is a late 19th Century word, coming to English in 1883. Perhaps oddly enough, ‘illiteracy’ has been part of the English language since the late 1600s, and even farther back, the same concept, was held by the word ‘illiterature’ in the 1590s. So, although, ‘illiterate’ make seem to appear linguistically what ‘literacy’ is not, it is the other way around, with ‘literacy’ appearing later in the language to describe the converse of ‘illiterate.’ ‘Literate’ stood all on its own to mean ‘educated and instructed’ in the early 15th Century; it is derived from the Latin litteratus/literus, meaning, ‘the one who knows letters,’ which are terms Latin speakers stole from the structure of the Greek word grammatikos, from which we get the equally studious ‘grammar.’
So, if a ‘literate’ knows ‘letters’, what are these letters? ‘Letter’ appeared on the scene in the early 1200s has an Old French word meaning ‘graphic symbol or written character’ and is derived from Latin, which again, took its cues from Eutruscan and Greek before it (in loose words that meant ‘tablet’ or some part of an alphabet). The Old French term ‘letter’ also encompassed the written places where these pieces of the alphabet happened: in missives and notes, document and record, and in writing and learning (which would become ‘literature’). Before ‘letter’ was borrowed from Old French, speakers of what would become English, used Germanic and Old English words like bocstæf and buchstabe and buohstab–quite literally translated as ‘book staff’.
As a side note, I should note that Old English already had terms in place that meant the same things at Latin and Greek’s ‘letters’ and ‘grammar’; “Staff” is an Old English term that means not only the walking stick that supports you, but also staf supports, places, fastens and holds together stæfcræft, the Old English term for “grammar.” In Old English back to Sanskrit, ‘staff’ is at once letter, pillar, stem, and a group of military support, collapsing the whole pen/sword debate about who is mightier… a ‘staff’ is both pen and sword.
From ‘literate’ is added ‘cy’ in the late 19th Century. With the advent of institutional education and formalized public schooling, ‘literacy’ described a state of being, a condition, of being ‘literate’, and its usage narrowed in reference to reading and writing from the earlier collocations of documentation and record.