lapsus digitorum

noun /ˈlæpsəs.dɪʤɪˈtɔːɹəm,ˈlæpsuːs.dɪʤɪˈtɔːɹəm/

A spelling error in signing.

We remember an instance of a little girl who had picked up the phrase “good-night” from the elder pupils, spelling each letter on her fingers, using it as they did, when bidding adieu to the teacher who conducted evening prayers; but she showed her misapprehension of its exact meaning, by saying “good-night” to her teacher after morning school. It was no mere lapsus digitorum, for having not yet been taught the names of the divisions of time, she had confounded the particular term “good-night,” with the general one “good-bye.”