signal: [16] Latin signālis meant ‘of a sign’ (it was derived from signum ‘mark, token’, source of English sign). It came to be used as a noun, and passed via medieval Latin signāle into Old French as seignal. This was later relatinized into signal, in which form it was taken over by English. The adjective signal ‘conspicuous’ came from the same ultimate source, but via a more circuitous route. The Italian version of the noun signal is segnale. From it was derived the verb segnalare ‘make famous’, whose past participle segnalato gave French signalé – whence English signal. => sign
