Adjective reduplication
Chinese adjectives can be used in a reduplicated form.
A one-syllable adjective “A” reduplicates as AA; a two-syllable “AB” usually as AABB.
Reduplication usually intensifies the adjective, or adds a warm, affectionate tone.
1. One-syllable adjectives
A → AA
大 → 大大 — big → nice and big
小 → 小小 — small → tiny little
2. Two-syllable adjectives
AB → AABB
漂亮 → 漂漂亮亮 — pretty → all dressed up and lovely
Examples
我再给她买个大大的生日蛋糕
我再给她买wǒ zài gěi tā mǎiI'll also buy her
大大的dàdà denice and big
生日蛋糕shēngrì dàngāobirthday cake
Here 大大 intensifies the adjective.
这只猫小小的，真让人喜欢
这只猫zhè zhī māothis cat
小小的xiǎoxiǎo detiny little
真让人喜欢zhēn ràng rén xǐhuanyou can't help liking it
Here 小小的 conveys not just smallness but fondness.
一雪的女儿每天都漂漂亮亮的
一雪的女儿Yìxuě de nǚ'érYixue's daughter
每天都měitiān dōuevery single day
漂漂亮亮的piàopiàoliangliang delooking lovely
Here 漂亮 is a two-syllable adjective, so it reduplicates as 漂亮 → 漂漂亮亮.
Quick rule
One syllable: A → AA
大 → 大大 — nice and big
小 → 小小 — tiny little
Two syllables: AB → AABB
漂亮 → 漂漂亮亮 — looking lovely
Reduplication either intensifies the quality, or adds warmth and affection to the sentence.