Abarim Publications' online Biblical Hebrew Dictionary
סמך
The verb סמך (samak), meaning to lean or lay upon, is mostly used in the phrase, "laying on of hands" (Exodus 29:10, Numbers 8:12), but it's also used in the regular sense of leaning (like a man with his hands against the wall - Amos 5:19), or figuratively, in the sense of God's wrath leaning on someone (Psalm 88:7) or someone's aggression leaning on a nation (Ezekiel 24:2).
But often this verb is used in the sense of support, uphold or sustain - food sustains people (Genesis 27:37); works of God's hands are upheld forever (Psalm 111:8); people are saved (or not) by God (Isaiah 63:5).
A noun derived from this root, סמך (samekh), occurs as the name of the samekh, the fifteenth letter of the Hebrew alphabet.