General Definition: 1. The Auslan sign BOIL and the action of something that decreases in height. As a Verb or Adjective: 1. Boil a liquid so that some the water evaporates. A technique used to thicken sauces, or to make the flavour stronger. English = reduce. Note: 1. There appears to be no commonly used Auslan sign for REDUCE (but some signers represent this visually using these depicting signs, once they have established the topic). If you know a sign for REDUCE used by you or other Auslan users (deaf people or interpreters) please go to "Report missing sign" and supply details. Thank you.