chatter, rattle on
喇 centers on rapid, repetitive vocal noise: chattering or rattling on. The given meanings both describe continuous, often meaningless talk.
喇 combines 口 (mouth) with 剌, which likely contributes the sound. The character is used phonetically to represent chattering sounds.
The mouth radical 口 beside 剌 suggests a mouth producing a rapid, cutting sound like chatter. Imagine a mouth rattling on like a sharp tool.
For ラツ, picture a person chattering so fast it sounds like 'rats rats rats': rats -> ラツ, tying the rapid chatter to the reading.
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