The highest register of the human voice, lying above the modal register and falsetto.

plural of whistle register

Of an instrument or machine: recording its own operations.

A device (originally fitted with a pen, but now purely electronic) that records all numbers called from a particular telephone line.

plural of pen register

Synonym of baby talk

The practice, of cats and some other animals, of placing their hindfeet in the same place as (i.e. in the prints left by) their forefeet.

(nautical)

an official list maintained by the land registry of land, buildings and their particulars.

plural of land register