Abarim Publications' online Biblical Hebrew Dictionary
It's not known what meaning the root עקר ('qr) might have carried, but judging from its derivatives, it generally denotes a removal or uprooting or a thwarting of some proper forward motion of living things:
- The masculine noun עקר ('eqer), meaning offshoot or member. It's used only once, in Leviticus 25:47.
- The verb formed from the preceding noun: עקר ('aqar), meaning to pluck or uproot. It's used twice: Ecclesiastes 3:2 and Zephaniah 2:4.
- The verb עקר ('aqar), which is identical to the preceding one, and is either derived from the same noun (and is thus pretty much the same verb), as is proposed by BDB Theological Dictionary, or it comes from the following noun, as is maintained by HAW Theological Wordbook of the Old Testament. The verb denotes the practice of hamstringing horses or other animals, for various reasons (Genesis 49:6, Joshua 11:6).
- The adjective (or noun, says HAW) עקר ('aqar), meaning barren or barrenness of either males or females, mankind or animals (Deuteronomy 7:14; Genesis 11:30, Exodus 23:26).
- Perhaps the masculine noun עקרב ('aqrab), meaning scorpion, is also part of this root (Deuteronomy 8:15, 1 Kings 12:11).