dvādaśāyatanāni

Sanskrit:द्वादशायतनानि dvādaśāyatanāni
Pāli:द्वादसायतनानि dvādasāyatanāni
Tibetan:སྐྱེ་མཆེད་བཅུ་གཉིས་ skye mched bcu gnyis
Thai: อายตนะ 12
English: 12 entrances

Grammatical information:
This is a "dvigu" compound(samāsa) with dvādaśa(twelve) + āyatana as āyatanāni (vocative - neuter - plural)

Further information:

A classification model for cognition of phenomena. This classification has 6-pairs of inner entrances and outer entrances for producing cognition within the kāmadhātu.

These inner entrances(āyatana) correspond with the outer entraces(āyatana) according to this list:

inner āyatana	outer āyatana
cakṣu (eye)	rūpa (form)
śrotra (ear)	śabda (sound)
ghrāṇa (nose)	gandha (smell)
jihvā (tongue)	rasa (taste)
kāya (body)	sparśa (touch)
mana (mind)	dharma (mind object)

In this 12 āyatana model, for first 5 types cognition, 3 components are needed, outer āyatana, corresponding inner āyatana, and the manāyatana. Eye, ear, nose, tongue, and body entrances (inner āyatana, which produce cognition of seeing, hearing, smelling, tasting and touching) are dharmas of “form-clarity” (rūpa-prasāda), a derivative type of form that can function as the basis (āśraya) for the corresponding consciousness (aśrita - supported) and corresponding object (ālambana - support). For the cognition of mind object, only the outer āyatana (dharmāyatana) and inner āyatana (manāyatana) are needed. Therefore, for each cognition, manāyatana is an essential, as all the 6 consciousnesses (ṣaḍvijñāna) are included in the manāyatana. The manāyatana also has ability to take the former moment of cognition of itself (of all 6 types), to produce the next cognition. Some scriptures describe the process leading to cognition as sequential arising (eg. outer, then inner, then manāyatana), while other scriptures describe them as simultaneous arising (eg. outer, inner and manāyatana arises at the same time).