From BiblePortal Wikipedia

Morrish Bible Dictionary [1]

1. demuth, 'likeness, representation.'   2 Chronicles 4:3;  Daniel 10:16;  Hosea 12:10 .

2. tabnith, 'pattern, form, structure.'   Psalm 106:20;  Psalm 144:12 .

3. temunah, 'form, appearance,' which may not imply likeness.   Numbers 12:8;  Deuteronomy 4:12,15,16 .

4. Three words derived from ὅμοιος, 'like, similar.'   Romans 5:14;  Hebrews 7:15;  James 3:9 .

Holman Bible Dictionary [2]

 2 Chronicles 4:3 Daniel 10:16 Psalm 106:20 Psalm 144:12 Numbers 12:8 Deuteronomy 4:12 2 Romans 5:14 Hebrews 7:15 James 3:9

Webster's Dictionary [3]

(1): ( n.) The quality or state of being similar or like; resemblance; likeness; similarity; as, similitude of substance.

(2): ( n.) That which is like or similar; a representation, semblance, or copy; a facsimile.

(3): ( n.) The act of likening, or that which likens, one thing to another; fanciful or imaginative comparison; a simile.

King James Dictionary [4]

SIMIL'ITUDE, n. L. similitudo.

1. Likeness resemblance likeness in nature, qualities of appearance as similitude of substance. Let us make man in our image, man in our similitude. Fate some future bard shall join in sad similitude of griefs to mine. 2. Comparison simile. Tasso, in his similitude, never departed from the woods. See Simile.

Vine's Expository Dictionary of NT Words [5]

 Romans 5:14Likeness Hebrews 7:15Like James 3:9Likeness

Cyclopedia of Biblical, Theological and Ecclesiastical Literature [6]

( דַּמוּת , a Physical resemblance,  2 Chronicles 4:3  Daniel 10:16; תִּבְנַית , a Pattern,  Psalms 106:20;  Psalms 144:12; תַּמוּנָה , a Shape,  Numbers 12:8;  Deuteronomy 4:12;  Deuteronomy 4:15-16; Ὁμοιότης , Ὁμοίωμα , Ὁμοίωσις , similarity in general). The word is now chiefly used in a figurative sense of a form of speech including the simple metaphor, or the extended comparison of various kinds, especially the two following of the latter.

1. The Allegory, a figure of speech, has been defined by bishop Marsh, in accordance with its etymology, as "a representation of one thing which is intended to excite the representation of another thing;" the first representation being consistent with itself, but requiring, or being capable of admitting, a moral and spiritual interpretation over and, above its literal sense. An allegory has been incorrectly considered by some as a lengthened or sustained metaphor, or a continuation of metaphors, as by Cicero, thus standing in the same relation to metaphor as parable to simile. But the two figures are quite distinct; no sustained metaphor, or succession of metaphors, can constitute an allegory, and the interpretation of allegory, differs from that of metaphor in having to do not with words, but things. In every allegory there is a two-fold sense the immediate or historic, which is understood from the words, and the ultimate, which is concerned with the things signified by the words. The allegorical interpretation is not of the words, but of the things signified by them; and not only may, but actually does, coexist with the literal interpretation in every allegory, whether the narrative in which it is conveyed be of things possible or real. An illustration of this may be seen in  Galatians 4:24, where the apostle gives an allegorical interpretation to the, historical narrative of Hagar and Sarah; not treating that narrative as an allegory in itself, as our A.V. would lead us to suppose, but drawing from it a deeper sense than is conveyed by the immediate representation.

In pure allegory no direct reference is made to the principal object. Of this kind the parable of the prodigal son is an example ( Luke 15:11-32). In mixed allegory the allegorical narrative either contains some, hint of its application, as Psalms 80, or the allegory and its interpretation are combined, as in  John 15:1-8; but this last passage is, strictly speaking, an example of a metaphor.

The distinction between the parable and the allegory is laid down by dean Trench (On the Parables, ch. 1) as one of form rather than of essence. "In the allegory," he says, "there is an interpretation of the thing signifying and the thing signified, the qualities and properties of the first being attributed to the last, and the two thus blended together, instead of being kept quite distinct and placed side by side, as is the case in the parable. According to this, there is no such thing as pure allegory as above defined. (See Allegory).

2. The Parable, as a form of teaching, differs from the Fable, (1) in excluding brute or inanimate creatures passing out of the laws of their nature, and speaking or acting like men; (2) in its higher ethical significance. It differs, it may be added, from the Mythus in being the result of a conscious deliberate choice, not the growth of an unconscious realism, personifying attributes, appearing, no one knows how, in popular belief. It differs from the Allegory in that the latter, with its direct personification of ideas or attributes, and the names which designate them, involves really no comparison. The virtues and vices of mankind appear, as in a drama, in their own character and costume. The allegory is self interpreting. The parable demands attention, insight, sometimes an actual explanation. It differs, lastly, from the Proverb in that, it must include a similitude of some kind, while the proverb may assert, without a similitude, some wide generalization of experience. So far as proverbs go beyond this, and state what they affirm in a figurative form, they may be described as condensed parables, and parables as expanded proverbs (comp. Trench on Parables, ch. 1; and Grotius on Matthew 13). (See Parable).

International Standard Bible Encyclopedia [7]

si - mil´i - tūd  : In the King James Version means either "an exact facsimile" (  Psalm 106:20 the King James Version, the Revised Version (British and American) "likeness";   Romans 5:14 , etc.), or else "the form itself" ( Numbers 12:8;  Deuteronomy 4:12 ,  Deuteronomy 4:15 ,  Deuteronomy 4:16 for temūnāh , "form" (so the Revised Version (British and American)); compare Likeness . the English Revised Version has retained the word in  2 Chronicles 4:3;  Daniel 10:16 (the American Standard Revised Version "likeness"), while the English Revised Version and the American Standard Revised Version have used "similitudes" in   Hosea 12:10 ( דּמה , dāmāh , "be like"). The meaning is "I have inspired the prophets to speak parables."