Most languages have a separate word for hot (temperature wise) and hot (spicy). It makes perfect sense! How many times have you been warned, putting that first fork of food into your mouth, ’Careful, it’s hot!’, only to wonder which hot is meant?
Now I am no expert on this but it appears to me that the Romans had the same problem with laugh and smile. There is a wonderful letter written by Gaius Plinius Caecilius Secundus in which he tells his friend Tacitus (yes, that Tacitus!) about his hunting trip. It consists of sitting by the nets with his books and tablets while others chase three boars into his trap. He begins the letter ridebis, et licet rideas. You will laugh, and it is permitted that you laugh. Or does he mean smile? The truth is, the Verb ridere can mean both.
In Pliny’s case the distinction is not so important, but what of Marcellus? It makes a huge difference whether he enters Augustus’ office and smiles to him or laughs at him! The situation is worse with Nouns. The entry for risus in the Cassell’s Latin Dictionary defines it as laughter, laughing, jeering, ridicule. But when you turn to the back to find an appropriate word for a smile, it suggests risus! And a risor one who laughs (or is it smiles?), is defined as a mocker!
Both the Cassell’s and The Oxford Latin Dictionary suggest that subridere means to smile, which I guess means that a smile is a kind of under-laugh. So I went with that. But, just to be clear, there is no matching Noun. There is another Verb that I may have used, adridere to smile at. But an adrisor is a flatterer, not a good thing to be in Ancient Rome. Then there is deridere, which I include only out of interest for its English Derivative. It means to laugh down at or deride. The whole situation is risible.
Augustus, the bank manager, rises out of his seat in order to greet Marcellus in a friendly manner. The artist smiles to Augustus.