IPA: //mɛˈtæl.əˌhaɪd//
KK: /mɛˈtæl.əˌhaɪd/
A white crystalline compound made from acetaldehyde, often used to kill snails and slugs.
Farmers use metaldehyde to protect their crops from slugs and snails.
Metaldehyde is formed from "meta-" (meaning beyond or change) and "aldehyde" (from the Latin "alcohol dehydrogenatum", meaning a compound derived from alcohol). The term refers to a compound that is a derivative of aldehyde, indicating a change in its chemical structure.
Think of 'meta-' meaning beyond or change, and 'aldehyde' as a compound derived from alcohol, which helps you remember that metaldehyde is a changed form of an alcohol-derived compound.