The word like is not well described by the traditional word categories. As I described last week, it is both a preposition and a conjunction with the same meaning. In fact the word like is used in many ways. Here are a few more:
like used as a conjunction (similar to): I did it like you told me.
like used as a preposition (similar to): The weather is like that in Australia.
like used as a verb (to find pleasant): He likes her.
like (liking) used as a gerund-noun (to find pleasant): He has a liking for hot curry.
like used as et cetera (etc / &c): He reads Dickens and the like.
like used as an approximating adverb: The candy cost something like a dollar.
like used as an adjective (similar): The store has many dresses of like design.
like as an auxiliary verb (nearly): The bread was so hard I like broke my teeth. *
(This auxiliary verb use is confusing, as the “exclamation” form below would make this mean you actually broke your teeth.)
like as a reporting verb (to indicate paraphrasing): He is like this homework is impossible. *
like as an exclamation: The test was like difficult. *
like as a postponed filler: He was running really fast, like. *
like as a fixed expression (closer to what is desired): That new price is more like it.
likely (or like) as a fixed expression (probably): It is as likely as not that he will go home.
(It is as like as not that he will go home.)
(Although they do exist, I recommend not using the forms marked with *.)
Some of these uses are more common than others. The verb like is common and is historically a different word. The use of like as an adjective is more common in UK English than American English, but correct in both. The use of like as an auxiliary verb or a postponed filler is rare, but found in some local UK varieties. Using like as a reporting verb, instead of the word says indicates that you are paraphrasing not quoting. As an exclamation the word like has no meaning of its own, but emphasises the next word or clause. Using like as a reporting verb or as an exclamation is slang and not widely accepted. The less common uses are easily ignored.
The verb form of like is a different word and goes back to the Old English lician (to find pleasant). As an adjective it was a Middle English shortening of the Old English gelic (similar). The adjective started being used as a noun, preposition and auxiliary verb about eight hundred years ago. The word like was then used as a conjunction about six hundred years ago. The word as a postponed filler is about two hundred years old. Both fixed expressions (that is more like it and as likely as not) are about a hundred years old. The exclamation and reporting verb are only about fifty years old and will hopefully die out. The comparative liker and superlative likest died out about three hundred years ago. It is best to avoid any use that is recent or has died out.
The words we used to describe words (noun, adjective, conjunction, preposition) are all from Latin. English is a Germanic language and not descended from Latin. Sometimes in English there are words that do not fit neatly into these foreign categories. English is a messy language. It will change depending on what is used or ignored. The uses of the word like you choose will change the future of English.