IPA: /ˈræt̬.əl.iːr/
KK: /ˈræt̬.əl.iːr/
Describing something that makes a series of short, sharp sounds, often in a shaky or unsteady manner.
The old car had a rattlier engine than the new one.
Comparative: rattlier
Superlative: rattiest
The word 'rattlier' is derived from 'rattle' (from Middle English *ratlen*, meaning to make a rapid succession of short, sharp sounds) and the comparative suffix '-ier' (meaning more). Thus, 'rattlier' means making more rattling sounds than something else.
Think of something that makes more rapid, sharp sounds ('rattle') — the '-ier' indicates it is more so. This helps you remember that 'rattlier' refers to something that rattles more.