Semi- is a 5 letter English word. It's valid Scrabble word worth 6 points. It's valid Words with friends word worth 7 points.
You can make 32 anagrams from letters in semi- (-eims).
Middle English Latin sēmi-; cognate with Old English sōm-, sām- half (modern dial. sam-), Old High German sāmi-, Sanskrit sāmi-, Greek hēmi-; cf. sesqui-
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