can someone tell me what seme and uke means please(￣∇￣")

thank youヾ(☆▽☆)

Adding on: If I remember correctly it was also a play on a sport/baseball terms? Seme is the pitcher (top in the bl/yaoiverse) and Uke is the receiver (bottom).

Adding in the Chinese word for them too just incase you read Chinese BL.
GONG/SEME AND SHOU/UKE