When I was in my late teens, my father (a chemical engineer) took an interest in quantum mechanics.  Two words from his conversation at that time stuck in my mind, namely Hamiltonian and eigenfunction.  The former was almost certainly due to the Scottish part of my ancestry, but with the latter it was the word itself.

Indeed, it at first sight seems quite an intimidating word, along with its relatives eigenvalues and eigenvector.  Fear not – I will show you that it despite its fearsome bark, it has a very soft bite.

It may surprise those who know of my Ulster Protestant background that I am something of a fan of Flannery O’Connor.  As yet, I have not delved into her novels, but I have read all her stories, and also Mystery and Manners : Occasional Prose, from which I take the following

A multiplet is a simple thing to describe: it is a collection of several identical or nearly identical things. Here, however, a difficulty arises because a "multiplet" is a manifestation of symmetry groups, and symmetry groups are tough objects to discuss. So if in a scientific paper you write "the new hadron might belong to a SU(3) multiplet", you have the additional trouble that you need to avoid discussing group theory to an unwilling listener. What is SU(3) ? Do we actually care?