tong- / Indo-European roots
To think, feel.
1. thank from Old English thanc, thought, good will, and thancian, to thank, from Germanic *thankaz, thought, gratitude, and *thankōn, to think of, thank.
2. bethink, think from Old English (bi)thencan, to think, from Germanic *(bi-)thankjan.
3. thought from Old English (ge)thōht, thought, from Germanic *(ga)thanht- (*ga-, collective prefix; see kom)
4. methinks from Old English thyncan, to seem, from Germanic *thunkjan.
[Pokorny 1. tong- 1088.]