829: tittle Mar 16, 2017

There are a number of idioms relating to spelling that mean "be careful" including "mind your P's and Q's". Before the printing press, and therefore that phrase, people still had to be careful to "dot their I's and cross their T's", an action which could easily be overlooked especially when writing in cursive. The word for that dot over a lower case I is not only called a 'dot' but also a 'jot' and a 'tittle'. The last item of that list can also refer to the horizontal line on the T.  The Latin origin for this word, 'titulus', also gave English 'title' initially denoting a placard placed over an object, which is not too different from the modern understanding of that term. There is also a phrase "to jot and tittle" meaning literally to add the secondary marks to I and T respectively, but is used generally to mean, "add finishing touches". This phrase is said to have started with the line in Matthew 5:18 which translates to "For truly, I say to you, until heaven and earth pass away, not an iota[jot], not a dot, will pass from the Law until all is accomplished". It should be noted that 'iota' and 'jot' were once the same were, as explained here.