Sound-symbolism is the inherent link between the sound of a word and its meaning. The aim of this thesis is to gain an insight into the nature of sound-symbolism. There are five empirical chapters, each of which aims to uncover children and adults’ understanding of sound-symbolic words. Chapter 1 is a literature review of sound-symbolism. Chapter 2 is a cross-linguistic developmental study looking at the acquisition of sound-symbolism. Chapter 3 looks at childrens use of sound-symbolism in a verb-learning task. Chapter 4 looks at childrens use of sound-symbolism when learning and memorising novel verbs. Chapter 5 consists of two experiments looking at what exact part of a word is sound-symbolic. This study compared different types of consonants and vowels, across a number of domains in an attempt to gain an understanding of the nature of sound-symbolism. Chapter 6 looks at the potential mechanisms by which sound-symbolism is understood. This study is a replication of previous research, which found that sound-symbolic sensitivity is increased when the word is said and not just heard. There are therefore a total of five empirical chapters each of which attempts to look at the nature of sound-symbolic meaning from a slightly different angle.