พี่

From Proto-Tai *biːᴮ (“older sibling”).^[1]

In Southwestern Tai, cognate with Northern Thai ᨻᩦ᩵, Lao ພີ່ (phī), Lü ᦗᦲᧈ (pii¹), Shan ပီႈ (pīi), Ahom 𑜆𑜣 (pī).

In Northern Tai, cognate with Zhuang beix, Bouyei bix.

พี่ • (pîi) (classifier คน)

1. elder brother; elder sister.
2. older person.
3. (colloquial) superior; master; leader; boss.
4. used as a title or term of address
   1. used as a title for or term of address to an elder brother, elder sister, or older person; used by such person to refer to oneself when speaking to a younger brother, younger sister, or younger person.
   2. used as an affectionate title for or term of address to a beloved, older person; used by such person to refer to oneself when speaking to a beloved, younger person.
      • 18th century, เจ้าฟ้าธรรมธิเบศไชยเชษฐ์สุริยวงศ์, “บทเห่เรือ พระนิพนธ์เจ้าฟ้าธรรมธิเบศร”, in ประชุมกาพย์เห่เรือ‎^[2], Bangkok: โรงพิมพ์โสภณพิพรรฒธนากร, published 1917, retrieved 17 September 2019:

        ขาวสุดพุดจีบจีน เจ้ามีสีนมีศักดิ์ ทั้งวังเขาชังนัก แต่รักเจ้าคนเดียว

        kǎao sùt pút-jìip jiin · jâao mii sǐin pîi mii sàk · táng wang kǎo chang nák · dtɛ̀ɛ pîi rák jâao kon diao

        [My] whitest Chinese pinwheel, thou art of wealth, I am of worth. Though they, [the people] throughout the palace, hate [thee that] much, I [am] the only one that loveth thee.

   3. (colloquial) used as a title for or term of address to a superior, master, leader, or boss; used by such person to refer to oneself when speaking to when addressing a subordinate, inferior, or servant.