Bhagavad Gita, Chapter 14, Verse 13

अप्रकाशोऽप्रवृत्तिश्च प्रमादो मोह एव च । तमस्येतानि जायन्ते विवृद्धे कुरुनन्दन

aprakāśo'pravṛttiśca pramādo moha eva ca | tamasyetāni jāyante vivṛddhe kurunandana

Translation

Darkness, heedlessness, inertness, and error — these arise when Tamas is predominant, O descendant of Kuru.

— Alladi Mahadeva Sastri

Word meanings

aprakāśaḥ
darkness
apravṛttiḥ
non-forthgoing
ca
and
pramādaḥ
heedlessness
mohaḥ
delusion
eva
even
ca
and
tamasi
in (the state of) inertia
etāni
these
jāyante
are born
vivṛddhe
(in having become) increased
kurunandana
O rejoicer of the Kurus

Śaṅkarācārya's commentary

Darkness: absence of discrimination. Inertness: extreme inactivity, the result of darkness. Heedlessness and error are also the effects of darkness.