Lexical & Compositional Semantics

Lexical & Compositional Semantics

The field of communications is complex, but the basic principle comes down to one simple idea: The message being sent is the same as the one being received.

Many factors influence a recipient’s understanding of a message, and the sum of the interplay of these factors ultimately determines if the message is understood in the way the sender intends for it to be understood. Culture, experience, professional background, upbringing – these are all well-known factors in the equation, but among these is the concept of lexical and compositional understanding.

Does knowledge or understanding of a phrase equal understanding of the words or parts of speech contained within that phrase? The answer lies in the difference between lexical and compositional meaning, and we need to understand both to get to the heart of the issue.

Just as one cannot glean true meaning from a phrase or sentence based on mere lexical understanding, it is not likely that understanding of a sentence or phrase as a whole begets knowledge or understanding of the component parts of that sentence or phrase. For this reason, it is important from a linguistics perspective to acknowledge the distinction between the two, and understand how these different types of meanings combine to form overall meaning.

Semantics is defined as “the subfield of linguistics that studies meaning in language.” Semantics as a whole can be divided into two main fields – lexical semantics and compositional semantics. The difference between these two closely related ideas lies in the scope: lexical semantics deals with individual word meanings, while compositional semantics deals with how those lexical meanings combine to form more complex phrasal meanings. Before we compare these two ideas, let’s first take a look at what is meant by “meaning.”

Meaning of Meaning

Linguistic meaning can be broken into two distinct ideas: sense and reference. By sense, we mean to refer to the mental representation of a word’s meaning. Upon hearing the word “chicken” one can imagine a roughly chicken-esque shape, but for each individual person, additional details might figure into this meaning as well. Feathers, two legs, a squawk, lays eggs, etc. are all ideas that might be part of the sense we have for the word “chicken.” Reference, on the other hand, deals with the particular entities to which an expression refers – for instance, a specific chicken named “Pearl” or the name of a specific species of chicken. This means that the reference of an expression is reliant on knowledge of its sense, but not necessarily the other way around. For instance, knowing what a banana represents – its sense – does not mean you would be able to identify a banana sitting in a bowl of plantains. So, in order to gather meaning, we must consider sense and reference together.

Lexical Semantics

When one needs to know the meaning of a word, the typical response is to pick up a dictionary. This dictionary definition is known as the word’s denotation. As native speakers of English, we have experience with the overall rules and structure for speaking English as a language, are familiar with its pragmatics and typical usages, so the dictionary is a great tool for picking up the basic idea behind any new words we come across. But what if we remove that basic understanding, and rely on dictionary definitions alone to gather meaning?

Consider the word slimy. This word on its own has a well-known denotation, or dictionary definition – to be covered in slime (a thick slippery liquid). On its own, it can be used to describe a muddy pit or a boiled-over kitchen mess. However, in particular instances, this word can take on additional or different meanings. When applied to a person (the slimy nightclub owner), for instance, there is an additional implied meaning, known as the word’s connotation. This additional meaning suggests a more negative feel for the person being described, something that isn’t lost on learned speakers of the language.

Suppose a person near you drops their cell phone, and as the pieces scatter across the ground in every direction, you hear them say “Oh that’s just fantastic.” As native speakers of English, we understand that this person is being ironic, however, English learners will likely turn to a dictionary or other similar source for a better understanding of the term “fantastic”, whereupon they will be a little confused. It isn’t likely that a person dropping their cellphone would think this was a truly “fantastic” thing to accomplish, but that’s what they said, isn’t it? If we did not understand sarcasm or irony, we wouldn’t be able to pick up the fact that what is said is actually the opposite of what is intended, and (strangely) this isn’t a mistake, it’s merely a means of expression – an exercise in pragmatics. Here, knowledge of the dictionary definition of “fantastic” would serve only if the additional concepts of sarcasm and irony were understood as well. Thus, it can be said a lexical understanding of the words alone would not be enough in this situation to gather the full meaning expressed.

Compositional Semantics

So, if knowledge of each word’s meaning isn’t enough for comprehension of a sentence or phrase as it is meant to be understood, how is the overall compositional meaning derived? Obviously, the overall meaning must have something to do with the meanings of those words contained within the phrase. “I don’t eat” and “I don’t drink”, for example, express different ideas because of the difference in lexical meaning between “eat” and “drink.” However, syntax, or the way in which the sentence is constructed, plays a role as well, as demonstrated below:

1. I like you.
2. You like me.

Both sentences express totally different propositions, however, they have the same words and each word has a clearly understood meaning. How is it that the meaning has changed? In sentence 1, “I” = subject, “you” = object, while in the second sentence these are reversed. This means that overall meaning relies not only on the meaning of each part but additionally on syntactic composition. This premise is known as the principle of compositionality. All languages contain an infinite number of word combinations, so memorization of each separate phrasal meaning is impossible. This means that in order to understand the meanings of new phrases, one must rely on individual word meanings combined with the specific syntactic structure.

In summary, the roles played by lexical and compositional semantics are equally necessary with regard to total understanding of a phrase or sentence. Knowledge of one without the other will invariably lead to miscommunication, and an understanding of denotation, connotation, and syntactical structure is necessary for the compositional understanding of the whole. Understanding the difference between these terms and how the ideas they represent interact is paramount to understanding the meaning of a phrase or sentence.