Also known, in its punctuation sense, as a virgule, a diagonal, a separatrix, a slant, a slash. There are technical usage and typesetting differences for the various types of forward slashes -- for example, the solidus was originally used for separating currency amounts, such as 2∕6d meaning 2 shillings 6-pense, where the / was a drawn out s for solidus meaning shilling, named after the Roman coin. In this usage, the / traditionally is typeset closer to 45° than the more upright standard slash. The virgule, on the other hand, is the forward slash used to indicate a linebreak when writing out a poem or song lyrics in running prose -- in this form, the / is more upright and thinner, and traditionally has a space on either side. As you can tell from the shilling mark, the name is from the coin, the name of which is related to solid, referring to its monetary status, because when it was newly issued, replacing the increasingly debased aureus as the gold coin of the empire.
It's like he talks in verse / I can almost hear a solidus / between each phrase.