Family & Relationships

Concept: Uchi (Inside) vs Soto (Outside)

Japanese uses different words depending on whose family you are talking about.
My Family (Humble/Uchi): Used when talking to others about your own family.
Others' Family (Honorific/Soto): Used when referring to someone else's family, or addressing your own elders directly.

Grandfather
祖父
そふ
Grandmother
祖母
そぼ
Father
ちち
Other: パパ
Mother
はは
Other: ママ
Older Brother
あに
Older Sister
あね
Siblings
兄弟
きょうだい
Younger Brother
おとうと
Younger Sister
いもうと

Extended & In-laws

Husband
おっと
Other: 主人 (しゅじん), 旦那 (だんな)
Wife
つま
Other: 家内 (かない), 嫁 (よめ)
Child
子供
こども
Son
息子
むすこ
Daughter
むすめ
Grandchild
まご
Uncle
叔父/伯父
おじ
Aunt
叔母/伯母
おば
Cousin
従兄弟/従姉妹
いとこ
Nephew
おい
Niece
めい
Father-in-law
義父
ぎふ
Mother-in-law
義母
ぎぼ

Other Relationships

Friend
友達
ともだち
Boyfriend
彼氏
かれし
Girlfriend
彼女
かのじょ
Lover
恋人
こいびと
Best Friend
親友
しんゆう
2hongo - Japanese Dictionary with Context