The Chinese word for grandfather is
祖父

zǔ fù

Chinese Definition

grandfather
1. 名词. 爷爷、祖父、姥爷、外祖父
Components
祖
1. ancestor; forebear; forefather
2. grandparent; grandfather or grandmother
3. founder
4. (literary) to follow the example of; to pattern after
5. . Zu
^祖 ^沖-之 - Zu Chongzhi (Chinese astronomer and mathematician during the Liu Song and Southern Qi dynasties)
父
1. father
父親 (fùqīn) - (formal) father
父母 (fùmǔ) - parents; father and mother
父子 (fùzǐ) - father and son
父女 (fùnǚ) - father and daughter
父輩 (fùbèi) - one's father's generation
家父 (jiāfù) - (humble) my father
生父 (shēngfù) - biological father
養父 (yǎngfù) - adoptive father
繼父 (jìfù) - stepfather
天父 (tiānfù) - (Christianity) Heavenly Father
國父 (guófù) - father of a nation; (specifically) Father of the Republic (Sun Yat-sen)
雜交水稻之父 (zájiāo shuǐdào zhī fù) - (specifically) Father of Hybrid Rice (Yuan Longping)
Antonyms: 母
2. (Used to address a male elder member of a family.)
祖父 (zǔfù) - paternal grandfather (one's father's father)
伯父 (bófù) - paternal uncle (father's elder brother)
叔父 (shūfù) - paternal uncle (father's younger brother)
岳父 (yuèfù) - father-in-law (wife's father)
舅父 (jiùfù) - maternal uncle (mother's brother)
姨父 (yífù) - maternal uncle (husband of mother's sister)
姑父 (gūfù) - paternal uncle (husband of father's sister)
Antonyms: 母
3. (literary, respectful) old man; elderly man
漁父fǔ (yúfǔ) - old fisherman
田父fǔ (tiánfǔ) - old farmer
4. (literary) Alternative form of 甫 ((honorific suffix used after a man's name;) courtesy name)
^梁父fǔ山（^梁甫山） (Liángfǔshān (Liángfǔshān)) - Mount Liangfu (alternately, Mount Liangfu) (in Shandong, China)

Translations for 父 and their definitions

爺爺
1. n. (colloquial) paternal grandfather
2. n. (colloquial) (Term of address for an elderly man.)
3. n. (dialectal Mandarin) maternal grandfather
4. n. (dialectal Mandarin, dialectal Jin) sun
5. n. (dialectal) father