A tense formative is an affix that indicates a change in tense. The tense formative in English is the suffix -ed as in I walk (present tense) and I walked (past tense). In Greek, the tense formative is an infix as the κα in λελυκαμεν is a tense formative indicating the perfect tense. Other tense formatives in Greek are (the more common are bolded):
- future active tense σ
- Liquid future active εσ (BBG 20.11)
- first aorist active σα
- first aorist active liquid α
- aorist passive θη
- future passive θησ
- second perfect active α (BBG 25.14)
- perfect active participle κ