From BiblePortal Wikipedia

Vine's Expository Dictionary of OT Words [1]

A. Adjective.

Yâqâr ( יָקָר , Strong'S #3368), “precious; rare; excellent; weighty; noble.” Although none of the 35 biblical appearances of this word occurs before First Samuel, they are scattered throughout the rest of the Bible.

First, yâqâr means “precious” in the sense of being rare and valuable: “And he took their king’s crown from off his head, the weight whereof was a talent of gold with the precious stones: and it was set on David’s head” (2 Sam. 12:30). The emphasis is on the nuance “rare” in 1 Sam. 3:1: “And the word of the Lord was precious in those days; there was no open vision.”

Second, the word can focus on the value of a thing: “How excellent is thy lovingkindness, O God!” (Ps. 36:7).

Third, this word means “weighty” or “noble”: “A little foolishness is weightier than wisdom and honor” (Eccl. 10:1, NASB); like dead flies which make perfume stink, so a little foolishness spoils wisdom and honor—it is worth more in a negative sense (cf. Lam. 4:2).

B. Verb.

Yâqar ( יָקַר , Strong'S #3365), “to be difficult, be valued from, be valued or honored, be precious.” This verb, which occurs 11 times in biblical Hebrew, has cognates in Ugaritic, Arabic, and Akkadian. The word means “to be precious” in 1 Sam. 26:21: “Then said Saul, I have sinned: return, my son David: for I will no more do thee harm, because my soul was precious in thine eyes this day.…”

C. Noun.

Yeqâr ( יְקָר , Strong'S #3366), “precious thing; value; price; splendor; honor.” This noun, which appears 16 times in biblical Hebrew, is Aramaic in form. The word signifies “value or price” (Zech. 11:13), “splendor” (Esth. 1:4), and “honor” (Esth. 8:16). In Jer. 20:5 the word refers to “precious things”: “Moreover I will deliver all the strength of this city, and all the labors thereof, and all the precious things thereof.…”

Hastings' Dictionary of the New Testament [2]

The word is of frequent occurrence in the NT, and represents various Greek terms; ἔντιμος, τιμή, τίμιος, ἰσότιμος. The root idea is something of great worth, which also becomes precious or an honour to those who possess it. It is applied to jewels ( Revelation 17:4;  Revelation 18:12;  Revelation 18:16;  Revelation 21:11;  Revelation 21:19), to wood ( Revelation 18:12), to the fruit of the earth ( James 5:7), to costly stones used in building, i.e. stones of large size or of great price, like marble, etc. ( 1 Peter 2:4;  1 Peter 2:6,  1 Corinthians 3:12; cf.  2 Chronicles 3:6). It is also applied to the great promises ( 2 Peter 1:4), to the blood of Christ ( 1 Peter 1:19), and to faith, ‘equally precious faith’ ( 2 Peter 1:1, RVm_). The AV_ rendering of  1 Peter 2:7, ‘Unto you therefore which believe he is precious’ is changed in RV_ to ‘For you therefore which believe is the preciousness.’ In this passage the RVm_ ‘honour’ is to be preferred (sec Honour).

John Reid.

King James Dictionary [3]

PRE'CIOUS, a. L. pretiosus, from pretium, price. See Praise.

1. Of great price costly as a precious stone. 2. Of great value or worth very valuable.

She is more precious than rubies.  Proverbs 3

3. Highly valued much esteemed.

The word of the Lord was precious in those days there was no open vision.  1 Samuel 3

4. Worthless in irony and contempt.

Precious metals, gold and silver, so called on account of their value.

Webster's Dictionary [4]

(1): ( a.) Of great price; costly; as, a precious stone.

(2): ( a.) Of great value or worth; very valuable; highly esteemed; dear; beloved; as, precious recollections.

(3): ( a.) Particular; fastidious; overnice; overrefined. Cf. Precieuse, Preciosity.

(4): ( a.) Particular; fastidious; overnice.

International Standard Bible Encyclopedia [5]

presh´us (stands for 17 different words, chief of which are יקר , yāḳar  ; τίμιος , tı́mios ): (1) Generally in the literal sense, "of great price," "costly," "expensive," of material things (e.g.   Proverbs 1:13;  Jeremiah 20:5;  Mark 14:3 the King James Version), especially of precious stones (  2 Samuel 12:30;  2 Chronicles 3:6;  1 Corinthians 3:12 the King James Version, etc.). (2) Sometimes "of great moral (non-material) value." "Precious in the sight of Yahweh is the death of his saints" (  Psalm 116:15 ); "his precious and exceeding great promises" ( 2 Peter 1:4 ); compare  Psalm 139:17;  2 Peter 1:1 . The literal and the moral senses are both involved in the expression, "knowing that ye were redeemed, not with corruptible things,... but with precious blood" ( 1 Peter 1:18 ,  1 Peter 1:19 ). "Preciousness" (τιμή , timḗ ) occurs in  1 Peter 2:7 the American Standard Revised Version, the English Revised Version, for the King James Version "precious."