ใคร

Blend of คน (kon, “person”) +‎ ไร (rai, “what”).^[1]

Compare the dialectal ไผ (pǎi), from Proto-Tai *pʰaɰᴬ, from which the following are also derived: Northern Thai ᨹᩲ; Isan ใผ, ไผ; Lao ໃຜ (phai); Lü ᦺᦕ (ṗhay); Shan ၽႂ် (phǎue); Tai Nüa ᥚᥬᥴ (pháue); Aiton ၸၞ် (phaü); Ahom 𑜇𑜧 (phaw), 𑜇𑜨𑜧 (phow).

ใคร • (krai)

1. (interrogative) who; which person; what person?
2. whoever; anyone; someone; everyone; they (people in general).

   ใครก็ช่วยไม่ได้

   krai gɔ̂ chûai mâi dâai

   No one can help.
   (literally) Whoever [they are], [they] cannot help.

   ถามใครก็บอกว่า...

   tǎam krai gɔ̂ bɔ̀ɔk wâa ...

   [I] asked everyone [and they] told [me] that...

   ไม่อยากกวนใคร

   mâi yàak guuan krai

   [I] don't want to disturb anyone.

3. person; one.

   ใครบางคน

   krai baang-kon

   some person; someone