avidya (अविद्या, avidyā) = (nom. sg. f.) ignorance; confusion; lack of insight
kshetram (क्षेत्रम्, kṣetram) = (acc. sg. n./nom. sg. n. from kshetra (क्षेत्र, kṣetra)) field; pasture; source
uttaresham (उत्तरेषाम्, uttareṣām) = (g. pl. m./g. pl. n. from uttara (उत्तर, uttara)) the succeeding or next ones
prasupta (प्रसुप्त, prasupta) = (iic.) dormant; latent
tanu (तनु, tanu) = (acc. sg. n./nom. sg. n.) weak; young; incipient
vichchhinna (विच्छिन्ना, vicchinnā) = (nom. sg. f) full fledged; full grown; robust
udara (उदार, udāra) = (g. pl. m./g. pl. n./g. pl. f.) powerful; overwhelming; massive
anam (आणाम्, āṇām) = from all these

In his Yoga Sutrani (योग सूत्रानि, Yoga Sūtrāni), Patanjali (पतञ्जलि, Patañjali) describes the five obstacles (kle“sa (क्ले“स, kle“sa)) that render the path of the spiritual aspirant difficult. Of these five obstacles, avidya (अविद्या, avidyā) is mentioned first because it forms the basis for the other four.

No matter how long you practice yoga, you will always need to deal with avidya (अविद्या, avidyā). It can manifest itself in various ways and settings, and in the best case scenario is in a latent state that can become active and dominant even in experienced yogis. Hence in some cases wise men are controlled by avidya (अविद्या, avidyā) in some areas of their lives.
This reminds me of something that happened with my esteemed and beloved teacher B.N.S. Iyengar, who while giving a talk on yoga philosophy entitled “The role of women in society” expressed the view that “women are property.”

My fellow student, a young female yoga teacher from the USA, was of course incensed and launched into an angry discussion with Iyengar. Although he admitted that many women are more intelligent than men and are perfectly capable of thinking for themselves, he was simply unable to get past the idea that women are merely property. He put it this way:

“Look, first you are a child, then you are the property of your father. When you get married, you become the property of your husband. If you get widowed, you become the property of your sons.”

This discussion went on for several hours, during which time it became obvious that as an elderly man Iyengar was simply unable to think of women’s role in any other way. On the other hand, my fellow student couldn’t understand why a man who had studied yoga philosophy for so many years was unable to let go of this outmoded view of women. Both Iyengar and my fellow student were manifesting avidya (अविद्या, avidyā), i.e. a lack of understanding that afflicted these otherwise insightful human beings in this particular sphere. Neither of them were able to understand on account of cultural differences.

As a yogi, you always try to be aware of the fact that avidya (अविद्या, avidyā) can occur at any time. If you aren’t sufficiently vigilant about yourself, even a latent lack of insight can be activated and totally dominate you.