The part of speech of a word (or phrase) is its type in terms of what kind of idea the word communicates and its function in a sentence.
Anagram Genius makes heavy use of these categories in order to choose a word-order for each anagram it generates and to score the best word-order according to how grammatical the result. As a user of the software an understanding of parts of speech is only necessary if you wish to maintain any custom dictionaries or add words at the Word Stage. If you do, this (very informal) guide should serve as an introduction:
Nouns are words that denote things. They could be the name of someone or something (a proper noun) or the word used to identify a class of things, e.g. "dog", "person", "mountain", "country".
Nouns can be singular, plural or possessive.
A singular noun is where the word denotes a single thing, e.g. "mountain", "Bill Clinton", "New Zealand".
A plural noun is where more than one thing is denoted. Plural nouns usually (but not always) end in "s", e.g. "dogs", "countries", "problems", "ideas".
Possessive nouns are nouns which are modified to show that something belongs to the thing denoted (grammatically they are used similarly to adjectives). They can be singular or plural and usually end in "'s" (for singular possessives) or "s'" (for plural), e.g. "Bill Clinton's", "freedom's", "John's", "customers'".
As whether a possessive noun is singular or plural has no impact on its grammatical usage, Anagram Genius does not need to distinguish between the two.
The next big class of words are Verbs. Verbs are words which denote the performing of an action.
Most regular verbs in English have four forms:
The base form is the main word for the verb and has several uses, e.g. "heat" - to warm something up. It is used for most forms of saying that this action is done in the present, (e.g. I heat, you heat, we heat, they heat), as part of the infinitive with "to" (to heat) and for expressing the future tense (he will heat).
The -s form is the word for saying that a singular noun is doing something in the present (the third person singular). It usually ends in "s", e.g. "heats" - "he heats", "the fisherman heats his dinner".
The past is the form of the verb for saying the action was done in the past. It often (but not always) ends in "ed", e.g. "heated" - "He heated", "The soup was heated", "They heated the water until it boiled". Some examples of pasts that do not end "ed" are "ran", "gave", "was" and "spoke".
The present participle refers to the action being done continuously in the present and usually ends "-ing", e.g. "heating". This form can also be treated grammatically like a noun referring to the action that the verb denotes.
In addition to their basic forms, verbs can be transitive or intransitive. Transitive verbs denote actions which are done to an object: i.e. they need a noun after them, e.g. "destroy". Intransitive verbs are verbs which can just be done without having to be done to something. e.g. "sleep". "To sleep something" doesn't make sense - you normally just sleep. However, it isn't possible to just "destroy" and for the meaning to be fully understood - one always destroys something so destroy is transitive.
Many verbs are both transitive and intransitive. This can be because they have different individual senses from both categories. (e.g. "run" has an intransitive sense similar in meaning to sprint and a transitive sense meaning to administer something.) Another possibility is that the object being acted on doesn't need to be specified but can be, e.g. To eat. You can "be eating" or you can "be eating chicken".
Information about transitivity is important to Anagram Genius as it needs to know how to score a word-ordering of an anagram where a noun follows a verb form.
Adjectives are words which describe things, e.g. "big", "small", "green", "deep".
Apart from the normal form of the adjective there are two other forms. A comparative adjective is based on the normal adjective but implies that it is more so than another thing. These words usually end in "er", e.g. "bigger", "smaller", "greener", "deeper".
A superlative adjective implies that of all things, the one being described is the most so. These words usually end in "est". e.g. "biggest", "smallest", "greenest", "deepest".
Many longer adjectives have no comparative and superlative form - the same meaning is communicated with the words "more" and "most" in combination with the base adjective form, e.g. "more outrageous", "most outrageous". The words "outrageouser" and "outrageousest" do not exist. Having said that, there is no reason why phrases such as "most outrageous" cannot be added to custom dictionaries in Anagram Genius and classified as superlative adjectives.
Adverbs describe how a verb is done and almost always end in "ly". e.g. "slowly", "hurriedly", "swiftly". They also modify adjectives, e.g. "dangerously thin".
Interjections are words or phrases which are said by themselves and communicate concisely a thought or emotion. When written they almost always have an exclamation mark after them, e.g. "Wow!", "Oh my God!".
Interjections are very useful for anagram creation as their presence does not affect the grammatical context of anything that follows, i.e. Anagram Genius is free to do almost what it likes with the remaining letters once an interjection has been removed by the search.
Anagram Genius also recognises something similar from its perspective which it terms a "complete sentence". These are short phrases which are not strictly interjections but can be said on their own, e.g. "No problem", "I hope so".
English has other parts of speech which exist and occur frequently but the number of words in these categories are small and it is unlikely you would want to add further ones to any custom dictionary. However, they are included here for completeness.
Conjunctions are words like "and" and "or" which join things together.
Pronouns are words like "he", "it" and "they" which act like nouns but are distinguished from them by grammarians.
Articles are words like "a", "this" and "the" which go before nouns.
Prepositions are words like "of" and "to" which often act in partnership with verbs.