a large number of fish swimming together as a group 鱼群 shoals of herring 鲱鱼群 Squid travel in shoals. 鱿鱼成群游动。
a small hill of sand just below the surface of the sea 浅滩；水下沙洲 The boat ran aground on a shoal. 船在浅滩搁浅了。
Word Originsense 1 late 16th cent.: probably from Middle Dutch schōle ‘troop’. Compare with school sense 9.sense 2 Old English sceald (adjective), of Germanic origin; related to shallow.