| Trilogie | trilogy |
| Trilog | trialogue |
| Tribologie | tribology |
| Trisomie | trisomy |
| Aerologie | aerology |
| Urologie | urology |
| Triage | triage |
| Triole | triplet |
| Tripolis | Tripoli |
| -ologie | -ology |
| Antrologie | arthrology |
| Areologie | areology |
| Arkologie | arcology |
| Horologie | horology |
| Oologie | oology |
| Petrologie | petrology |
| Tetralogie | tetralogy |
| Ufologie | ufology |
| Urologin | urologist |
| -logie | -logy |