-ea

The applicative extension is highly productive and follows strict vowel harmony rules based on the verb's root vowel:

• Mid-vowels (e, o): Use -ea. For example, soma (read) becomes somea (read to/for).
• High/Low vowels (a, i, u): Use -ia. For example, pika (cook) becomes pikia (cook for).
• Vowel-final roots: Insert an 'l' to prevent a vowel clash, creating -lea or -lia. For example, nunua (buy) becomes nunulia (buy for).
• Arabic loanwords: These do not follow root vowel harmony. Verbs ending in -i or -e simply add an -a to the end (e.g., rudi becomes rudia, samehe becomes samehea). Verbs ending in -u change the -u to -ia (e.g., jibu becomes jibia). Note that verbs ending in -au (like sahau) act like Bantu vowel-final roots and take -lia (sahaulia).
• Monosyllabic verbs: Because their stems are so short, they have specific forms. For example, la (eat) becomes lia (eat with/for), ja (come) becomes jia (come to/for), fa (die) becomes fia (die at/for), and nywa (drink) becomes nywea (drink at/with).

Crucial Rule: The applicative extension increases the verb's valency by adding a new object. This turns an intransitive verb into a transitive one (e.g., enda to endea), and a transitive verb into a ditransitive one, where the new beneficiary becomes the principal object and the original direct object stays as a secondary object. If this beneficiary is a person or animal, Swahili grammar strictly requires you to include an animate object marker in the verb. When an applicative verb is used with the passive -wa, this beneficiary becomes the subject of the sentence (e.g., Mtoto alinunuliwa kitabu - The child was bought a book).

Beyond meaning 'for' or 'to', the applicative can express a malefactive meaning, where an action happens to someone's detriment (e.g., Gari limeniharibikia - The car broke down on me). It is also used with the associative -a to express purpose or instruments, such as kalamu ya kuandikia (a pen for writing). Additionally, when applied to verbs of motion, the applicative indicates direction or motion towards a specific goal or destination (e.g., kimbia (run) becomes kimbilia (run towards), hama (move out) becomes hamia (move into)).