cross [OE] The word cross was initially used in English to refer to a monument in the form of a cross. The source is Old Norse kross, which in turn goes back to crux, a Latin word that gave us *crucial, crucible [LME] originally a night light of the sort that might be hung in front of a crucifix [ME], and *excruciating.

People cross their fingers [E18th] to ward off bad luck. What they are doing is making a miniature ‘sign of the cross’, whether they know it or not. To cross someone’s palm with silver is to pay them for a favour or service. It probably comes from the idea of tracing the shape of a cross on a fortune-teller’s palm with a silver coin before you are told what the future has in store.

In 49 bc Julius Caesar, having defeated the Gauls, brought his army south to fight a civil war against Pompey and the Roman Senate. When he crossed the Rubicon, a small river marking the boundary between Italy and the Roman province of Gaul, he was committed to war, having broken the law forbidding him to take his troops out of his province. Cross meaning ‘annoyed’ dates back to the 17th century. It derives from the nautical idea of a wind blowing across the bow of your ship rather than from behind, which produced the senses ‘contrary, opposing’, and ‘adverse, opposed’, and then ‘annoyed, bad-tempered’. Crosspatch [E18th] is based on the obsolete word patch meaning ‘fool, clown’, perhaps from Italian pazzo ‘madman’.