From the same as lach; freshness, i.e. Vigor:
see HEBREW lach
H3893. leach
[לֵחַ] noun masculine moisture, freshness (i.e. force, vigour); — suffix לֵחהֹ נָס וְלֹא Deuteronomy 34:7 and his freshness had not fled; read probably also בְּלֵחוֺ for בְּלַחְמוֺ ᵑ0 Jeremiah 11:19 (see לֶחֶם near the end; on Zephaniah 1:17 see לְחוּם).
לֶ֑חִי לְחִי, see לחה.