וְאֵ֛ת שֵׁ֥ם הַשֵּׁנִ֖י קָרָ֣א אֶפְרָ֑יִם כִּֽי־הִפְרַ֥נִי אֱלֹהִ֖ים בְּאֶ֥רֶץ עָנְיִֽי׃
And the name of the second called he Ephraim: ‘for God hath made me fruitful in the land of my affliction.’
Read kabbalistic (mystical) interpretation of Genesis 41:52: and classical mystical sources.