Compounding

Compounding

Compounding is the process of formation of new words by combining two or more words which could be a new word retains the meaning of the words that make it up (compositional) or have a much different meaning from the words of origin (noncompositional).
In it can be seen that the compounding and blending has significant difference either on the meaning of words and the process of forming new words. 

whereas compound, forming new words from the overall combined two or more words in which the meaning of a new word can be much different than the words that form it, or could be the meaning of the words came from.
Well, to clarify the understanding of the notion of compound, consider some examples of compound in the following table:

Origin said Compounding
Mentioned Above + abovementioned
Back + bite backbite
Chalk + board chalkboard
Dash + board dashboard
Ear earphone + phone
Farm + house farmhouse
Gear + box gearbox
Hair + dresser hairdresser
Iron + work ironwork
Jail + bird Jailbird
Key Keyboard + board
Lady + finger ladyfinger
Master + piece Masterpiece
News + letter Newsletter
Out + bound Outbound
Path + way Pathway
Rail + way Railway
Sand + man Sandman
Table + spoon tablespoon
Under + arm underarm
Vine + yard Vineyard
Wall + board Wallboard
Bitter + sweet Bittersweet
Black + bird Blackbird
Carry + over carryover
Blue + Blueberry berry
Compounding of the few examples above, it became clear that compounding is the formation of new words from the merger of the overall two or more words. And keep in mind here is that the meaning of a new word is not always based on the meaning of words that make it up. Example:
Blueberry means berries that are blue
Blackbird is a species of bird (name of bird species) and not black bird
Backbite means slander (not bite back)
Bittersweet could mean a mixture of feeling sad and happy, it could also mean a mix between bitterness and sweetness.
 

In Greek and Latin, in contrast to English, roots do not typically stand alone. So compounds are composed of bound roots. Compounds formed in English from borrowed Latin and Greek morphemes preserve this characteristic. Examples include photograph, iatrogenic, and many thousands of other classical words.
Note that compounds are written in various ways in English: with a space between the elements; with a hyphen between the elements; or simply with the two roots run together with no separation. The way the word is written does not affect its status as a compound. Over time, the convention for writing compounds can change, usually in the direction from separate words (e.g. clock work), to hyphenated words (clock-work), to one word with no break (clockwork). If you read older literature you might see some compound words that are now written as one word appearing with unfamiliar spaces or hyphens between the components.
Another thing to note about compounds is that they can combine words of different parts of speech. The list above shows mostly noun-noun compounds, which is probably the most common part of speech combination, but there are others, such as adjective-noun (dry run, blackbird, hard drive), verb-noun (pick-pocket, cut-purse, lick-spittle) and even verb-particle (where 'particle' means a word basically designating spatial expression that functions to complete a literal or metaphorical path), as in run-through, hold-over. Sometimes these compounds are different in the part of speech of the whole compound vs. the part of speech of its components. Note that the last two are actually nouns, despite their components.
Some compounds have more than two component words. These are formed by successively combining words into compounds, e.g. pick-up truck, formed from pick-up and truck, where the first component, pick-up is itself a compound formed from pick and up. Other examples are ice-cream cone, no-fault insurance and even more complex compounds like top-rack dishwasher safe.
There are a number of subtypes of compounds that do not have to do with part of speech, but rather the sound characteristics of the words. These subtypes are not mutually exclusive.

Keep in mind that the new word formed does not always have the type or class of the same word by word origin, for example: the word back (noun / adjective) and bite (verb) after becoming compound, class of words turned into backbite (noun). For a clearer look at some examples of the following compounds:
noun - noun + note book → notebook (noun)

adjective - noun → blue + berry blueberry (noun)

verb - noun + work room → workroom (noun)

noun - verb + breast feed → breastfeed (verb)

adjective - verb high + light → highlight (verb / noun)

verb - preposition break + up → breakup (noun)

preposition - verb run out + → outrun (verb)

adjective - an adjective bitter sweet + → bittersweet (adjective)

preposition - preposition in + to → into (preposition)
In terms of writing, the compound is usually written in a variety of forms of writing as described below:
1) The distance (space) between two words (compounded), for example: baby oil, coconut oil, olive oil etc.
2) Put the dash (hyphen) between two or more words, for example: city-state, the pick-up track etc.
3) The two words together without separation, for example: blackbird, backbite, masterpiece, ladyfinger etc.

NOTE: from the types of writing compound above, writing the most correct is that the very end (3rd). That's because in the semantics of compound means uniting two or more words (new words) without any separation or distance between words. So if two or more words combined with a separator (clock-work) or within (olive oil), the compound word is not compound.