Word formation in English

The English language has a genius for the formation of expressive compound words. Common examples include sun-stroke, pick-pocket, elbow-room, land-lord, humming-bird etc.

The two parts of a compound word are usually separated by a hyphen. However, in the case of many common compound words, the component parts have become so closely connected that they are now written as one word without any hyphen between them.

Examples are: sunstroke, landlord, pickpocket, overload etc.
And in the case of some other compound words, complete integration has been achieved by modifying one or both of the component parts.

For example, pass time is now written as pastime. In the same way, holy day has become holiday and prime rose has become primrose.
There are different types of compound words

Noun + noun

Examples are: master-piece, table-cloth, maid-servant, bread-winner, shoe-maker etc.

Noun + gerund

Examples are: wool-gathering, snake-charming, bull-baiting, sooth-saying etc.

Noun + adjective

Examples are: court-martial, knight-errant

Gerund + noun

Examples are: piping-hot, walking-stick, drawing-room, laughing-stock, skipping-rope etc.

Adverb + noun

Examples are: out-patient, over-load, fore-sight, under-tone, in-sight etc.

Verb + noun

Examples are: dare-devil, cut-throat, break-fast, spend-thrift, pass-port etc.

Adjective + noun

Examples are: short-hand, free-thinker, lay-man, hard-ware, strong-hold etc.

Present participle + noun

Examples are: humming-bird, flying-fish, loving-kindness etc.
Pronoun + noun

Examples are: he-goat

Possessive noun + noun (In this case, the apostrophe is usually omitted)

Examples are: sportsman, craftsman, statesman, hair’s-breadth, stone’s-throw