The first radical of this word is guttural; this affects the adjacent vowels.
Singular
Plural
Masculine
Feminine
Masculine
Feminine
תַּחְתִּי
tachti
lower
תַּחְתִּית
tachtit
lower
תַּחְתִּיִּים
tachtiyim
lower
תַּחְתִּיּוֹת
tachtiyot
lower
Singular
Masculine
תַּחְתִּי
tachti
lower
Feminine
תַּחְתִּית
tachtit
lower
Plural
Masculine
תַּחְתִּיִּים
tachtiyim
lower
Feminine
תַּחְתִּיּוֹת
tachtiyot
lower