ocean, sea, foreign, Western style
洋 centers on a vast body of water: the ocean or sea. The meanings 'foreign' and 'Western style' extend from the idea of things coming from across the sea.
洋 combines 氵 (water) with 羊, which likely contributes the sound. The character originally referred to a large body of water, and later gained the extended sense of 'foreign' from the idea of overseas.
Water 氵 and a sheep 羊: imagine a sheep floating on the ocean, having come from a foreign land across the sea.
For ヨウ, picture a sheep floating on the ocean and saying 'yo!' as it waves: yo -> ヨウ, the ocean-crossing sheep.
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the West; the Occident; Western countries
Western-style clothes (cf. traditional Japanese clothes)
Pacific Ocean
the East; the Orient; (East) Asia
ocean; sea
Western music; European music
Western painting
Pacific War (1941-1945)
Western-style; foreign
Western food; Western dish; Western cooking
Western style
ocean
Western book
on the sea; on the ocean; offshore
open sea; ocean
Western wine and spirits; Western liquor
(Western) dressmaking
Western-style room
blending of Japanese and Western styles
Antarctic Ocean
Atlantic Ocean
Western-style room
Western person; Westerner