| 1 | Latin | psychologia | — |
| 2 | Latin | -logia | -logy; the study of |
| 3 | Ancient Greek | -λογία | Base for nouns denoting the study of something,... |
| 4 | Ancient Greek | λόγος | That which is said: word, sentence, speech,... |
| 5 | Ancient Greek | λέγω | I put in order, arrange, gather; I choose, count,... |
| 6 | Proto-Indo-European | leǵ- | to gather, collect, with derivatives meaning to... |