Killed in translation

The language of the [6th]commandment itself leads to ... broad applications. The Hebrew verb ratsakh found in this commandment is translated 'murder' or 'kill'. We are familiar with 'Thou shalt not kill' from the KJV. The ESV ... translates 'You shall not murder.' Most often, ratsakh refers to killing that is unlawful or forbidden. It is not used for the killing of animals or for killing in war. That would suggest that the best translation here is 'murder,' not the more general 'kill.' However, the term differs from our English word murder in that it applies to manslaughter and negligent homicide. 

Relevant Scriptures
Deuteronomy 19:5 
Exodus 21:12-14
Numbers 35:9-34
Deuteronomy 19:1-3
Joshua 20:1-9

Matthew 5:21-26 [cf. Leviticus 19:17] * 
1 John 3:14-16 
James 1:20 
Matthew 18:15-20
Galatians 6:1-2

Since the commandment mandates love, its ramifications are exceedingly broad, broad enough to cover the whole of ethics from its distinct perspective. 

* on legitimate forms of anger see also: Psalm:7:11; John 2:13-17; Deuteronomy 32:21; Exodus 34:14; Numbers 5:11-31; Psalm 69; Psalm 109; Psalm 137; Psalm 139:19-22; Ephesians 4:26; Titus 1:7; Psalm 103:8.
on verbal abuse: 1 Samuel 25:9-42; 2 Samuel 16:7-8; 19:16-23; Proverbs 12:18

Notes on The Doctrine of the Christian Life (Theology of Lordship), p686-690