Dialectal plural for sharp or jagged pieces, possibly referring to buttermilk curds, butter shards, or spiky plant growths in rural speech.
From butter + jags (from jag, meaning a sharp projection or poke). This appears to be a regional folksy term combining dairy references with descriptions of pointed shapes.
English dialect words like butterjags are vanishing as communities homogenize—they represent the creativity of isolated groups who invented vivid descriptive terms that never made it into official dictionaries.
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