I like the explanation of ‘dhamma’ in Wikipedia:
The word dharma has roots in the Sanskrit dhr-, which means to hold or to support, and is related to Latin firmus (firm, stable)… It is derived from an older Vedic Sanskrit n-stem dharman-, with a literal meaning of “bearer, supporter”, in a religious sense conceived as an aspect of Rta.[22]
In the Rigveda, the word appears as an n-stem, dhárman-, with a range of meanings encompassing “something established or firm” (in the literal sense of prods or poles). Figuratively, it means “sustainer” and “supporter”…
Keeping the above root meaning in mind, if we read the Suttas thoroughly, we will find the word ‘dhamma’ has different meanings in different contexts. Sometimes it means ‘phenomena’, other times it means ‘principles’ & ‘law’, other times it means ‘Teaching/Doctrine’, other times it means ‘practices’, etc. In Hinduism, for example, the most common meaning is ‘duty’.
When ‘dhamma’ is used to ‘represent an image arising in the mind’, these images are ‘mind objects’ or ‘sense objects known only by the mind’; therefore distinguished from the five physical sense objects.
‘The six classes of consciousness should be understood.’
‘Cha viññāṇakāyā veditabbā’ti—That’s what I said, but why did I say it?
iti kho panetaṁ vuttaṁ. Kiñcetaṁ paṭicca vuttaṁ?Eye consciousness arises dependent on the eye and sights.
Cakkhuñca paṭicca rūpe ca uppajjati cakkhuviññāṇaṁ,Ear consciousness arises dependent on the ear and sounds.
sotañca paṭicca sadde ca uppajjati sotaviññāṇaṁ,Nose consciousness arises dependent on the nose and smells.
ghānañca paṭicca gandhe ca uppajjati ghānaviññāṇaṁ,Tongue consciousness arises dependent on the tongue and tastes.
jivhañca paṭicca rase ca uppajjati jivhāviññāṇaṁ,Body consciousness arises dependent on the body and touches.
kāyañca paṭicca phoṭṭhabbe ca uppajjati kāyaviññāṇaṁ,Mind consciousness arises dependent on the mind and thoughts/mind-objects.
manañca paṭicca dhamme ca uppajjati manoviññāṇaṁ.‘The six classes of consciousness should be understood.’
‘Cha viññāṇakāyā veditabbā’ti—That’s what I said, and this is why I said it.
iti yaṁ taṁ vuttaṁ, idametaṁ paṭicca vuttaṁ.This is the third set of six.
Idaṁ tatiyaṁ chakkaṁ.MN 148