I think the word you're looking for is Anupassanā
[abstr. of anupassati, cf. Sk. anudarśana] looking at, viewing, contemplating, consideration, realisation
It's used in compound words like Kāyānupassanā (and Vedanānupassanā, Cittānupassanā, and Dhammānupassanā).
The fact that the second 'a' in "Kāyānupassanā" is long (i.e. with an accent on it, 'ā') is I think a hint that it's a compound of two 'a's, i.e.
Kāya + anupassanā = Kāyānupassanā
Wikipedia's Vipassanā (Etymology) says ...
Vipassanā is a Pali word derived from the older prefix "vi-" meaning "special", and the verbal root "-passanā" meaning "seeing". It is often translated as "insight" or "clear-seeing". The "vi" in vipassanā has many possible meanings, it could mean to '[see] into', '[see] through' or to '[see] in a special way.
... so there's a "root" "-passanā" -- which doesn't have an independent entry in the PTS dictionary, it just says ...
- Passanā (p. 447) Passanā Passanā see anu˚, vi˚.
... i.e. referencing anupassanā and vipassanā.
The Sanskrit is Pashyana or Paśyana -- meaning "see", apparently.
Also there's https://www.buddha-vacana.org/toolbox/pref.html#anu which gives six possible meaning for the prefix "anu".
after, behind (motion viewed from the front backward).
ex: dhāvati: to run > anu·dhāvati: to run after
bala: military force > anu·bala: rearguard
bhāsati: to speak > anu·bhāsati: to speak after, repeat
for, towards an aim, on to, into, over to, forward (motion viewed from the back forward).
ex: pavecchati: to give, bestow > anu·pavecchati: to hand over
rodati: to cry, weep > anu·rodati: to cry for
pavisati: to enter > anu·pavisati: to enter into
ex: dayā: sympathy, kindness > anu·ddayā: pity
yoga: application, endeavour > anu·yoga: devotion, dedication
vitakketi: to consider, reflect > anu·vitakketi: to ponder over
according to, in conformity with, along.
ex: ñāta: kown, well-knwon > anu·ñāta: permitted, allowed
mati: opinion > anu·mati: consent, agreement
rūpa: form > anu·rūpa: conform
anu·dhamma: in conformity with the dhamma
karoti: to do > anu·karoti: to imitate
secondary, supplementary, inferior, minor, smaller.
ex: pabbajā: ascetic life > anu·pabbajā: discipleship in ascetism
majjha: average > anu·majjha: mediocre
pavatteti: to set in motion > anu·pavatteti: to keep in motion
each, every, one by one.
ex: disā: direction > anu·disā: each direction
pubba: previous, former > anu·pubba: 'each after the previous one' ie. gradual
pañcāha: five days > anu·pañcāha: every five days.