1968, Jamaican English (first in song title "Do the Reggay" by Toots & the Maytals), perhaps [OED, Barnhart] related to rege-rege "a quarrel, protest," literally "ragged clothes," variant of raga-raga, alteration and reduplication of English rag (n.).
regeneracy
regenerate
regeneration
regenerative
regent
reggae
regicide
regime
regimen
regiment
regimental
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