| Source of investor angst | 24 |
| Source of invigoration | 22 |
| Source of iodine | 16 |
| Source of iridescent buttons | 28 |
| Source of Irish breakfast tea, oddly | 36 |
| Source of iron | 14 |
| Source of iron or lead | 22 |
| Source of iron, e.g. | 20 |
| Source of irritation | 20 |
| Source of Islamic law | 21 |
| Source of Italian bubbly | 24 |
| Source of ivory | 15 |
| Source of J.M. Smucker's success? | 37 |
| Source of J.P. Morgan's fortune | 35 |
| Source of Jed Clampett's wealth | 35 |
| Source of Julius's instinctive impulses? | 44 |
| Source of jumbo eggs, in brief | 30 |
| Source of kerosene | 18 |
| Source of kerosene and paraffin | 31 |
| Source of knocking | 18 |
| Source of knowledge | 19 |
| Source of lacquer, varnish or tannin | 36 |
| Source of lacquer, varnish, or tannin | 37 |
| Source of lake effect snow in Cleveland | 39 |
| Source of lake-effect snow in Cleveland | 39 |
| Source of lanolin | 17 |
| Source of late election returns, with "the" | 53 |
| Source of lavender scent from the primate cage? | 47 |
| Source of laws | 14 |
| Source of lean meat | 19 |
| Source of lean red meat | 23 |
| Source of leather | 17 |
| Source of lecithin | 18 |
| Source of legal precedent | 25 |
| Source of legal precedents | 26 |
| Source of leucite and rhyolite | 30 |
| Source of licorice-flavored oil | 31 |
| Source of light | 15 |
| Source of light meat | 20 |
| Source of Lincoln's indebtedness | 36 |
| Source of linen | 15 |
| Source of linseed oil | 21 |
| Source of litmus | 16 |
| Source of livelihood | 20 |
| Source of local information | 27 |
| Source of lots of living-room arm-waving | 40 |
| Source of low pitches | 21 |
| Source of low pitches? | 22 |
| Source of low-alcohol wines | 27 |
| Source of low-fat meat | 22 |
| Source of lunch meats | 21 |
| Source of lysergic acid | 23 |
| Source of magic | 15 |
| Source of magic dust | 20 |
| Source of many a bead | 21 |
| Source of many a giraffe's meal | 35 |
| Source of many a proverb, for short | 35 |
| Source of many bills | 20 |
| Source of many calls | 20 |
| Source of many clones | 21 |
| Source of many computer errors | 30 |
| Source of many coughs | 21 |
| Source of many dialogues | 24 |
| Source of many English words that come to us via French | 55 |
| Source of many memories | 23 |
| Source of many news items | 25 |
| Source of many old pop songs | 28 |
| Source of many orders | 21 |
| Source of many patents, briefly | 31 |
| Source of many quotations, for short | 36 |
| Source of many quotes, for short | 32 |
| Source of many shelter dogs (abbr.) | 35 |
| Source of many Sicilian explosions | 34 |
| Source of many spills | 21 |
| Source of many tiny animals | 27 |
| Source of many troubles | 23 |
| Source of many waves? | 21 |
| Source of maple syrup | 21 |
| Source of marine ink | 20 |
| Source of martini additives | 27 |
| Source of mescal | 16 |
| Source of mesons | 16 |
| Source of metal | 15 |
| Source of milk | 14 |
| Source of milk for chèvre | 28 |
| Source of milk for some cheeses | 31 |
| Source of milk used for Romano cheese | 37 |
| Source of mints, at times | 25 |
| Source of mirth in some cities | 30 |
| Source of misery | 16 |
| Source of misgivings | 20 |
| Source of models | 16 |
| Source of modern music | 22 |
| Source of mohair | 16 |
| Source of money that's "spread" in nine puzzle answers | 68 |
| Source of moos or baas | 22 |
| Source of more pay or more play | 31 |
| Source of morning stimulation, maybe | 36 |
| Source of most of the names in "The Lion King" | 56 |
| Source of mother-of-pearl | 25 |