Questions & Answers about Gülümseme herkesi mutlu eder.
gülümsemek (with -mek/-mak) is the infinitive “to smile.”
gülümseme (with -me/-ma) is a noun, meaning “smiling” or “a smile.”
In Gülümseme herkesi mutlu eder, we need a noun as the subject, so we use gülümseme.
- herkes = “everyone” (nominative, basic form)
- herkesi = “everyone” in the accusative case (direct object)
- herkese = dative case (“to everyone”)
In this sentence “everyone” is what’s being made happy (a definite, specific group), so we mark it with the accusative suffix -i, giving herkesi.
Turkish often uses etmek (“to do/make”) after an adjective to form “make [someone] [adjective].”
Here mutlu = “happy,” so mutlu etmek = “to make [someone] happy.”
mutlu eder is the 3rd-person-singular form, “(it) makes [them] happy.”