diff --git a/Go/dictionary/dictionary.go b/Go/dictionary/dictionary.go
new file mode 100644
index 0000000..4f7940d
--- /dev/null
+++ b/Go/dictionary/dictionary.go
@@ -0,0 +1,35 @@
+package dictionary
+
+import "errors"
+
+type Dictionary map[string]string
+
+var (
+    ErrNotFound   = errors.New("could not find the word you were looking for")
+    ErrWordExists = errors.New("cannot add word because it already exists")
+)
+
+func (d Dictionary) Search(key string) (string, error) {
+    definition, ok := d[key]
+
+    if !ok {
+        return "", ErrNotFound
+    }
+
+    return definition, nil
+}
+
+func (d Dictionary) Add(key, definition string) error {
+    _, err := d.Search(key)
+
+    switch err {
+    case ErrNotFound:
+        d[key] = definition
+    case nil:
+        return ErrWordExists
+    default:
+        return err
+    }
+
+    return nil
+}
diff --git a/Go/dictionary/dictionary_test.go b/Go/dictionary/dictionary_test.go
new file mode 100644
index 0000000..fa4b7d8
--- /dev/null
+++ b/Go/dictionary/dictionary_test.go
@@ -0,0 +1,62 @@
+package dictionary
+
+import "testing"
+
+func TestSearch(t *testing.T) {
+    dictionary := Dictionary{"test": "this is just a test"}
+
+    t.Run("known word", func(t *testing.T) {
+        got, _ := dictionary.Search("test")
+        want := "this is just a test"
+
+        if got != want {
+            t.Errorf("got %q want %q given, %q", got, want, "test")
+        }
+    })
+
+    t.Run("unknown word", func(t *testing.T) {
+        _, err := dictionary.Search("unknown")
+        want := "could not find the word you were looking for"
+
+        if err == nil {
+            t.Fatal("expected to get an error")
+        }
+
+        if err.Error() != want {
+            t.Errorf("got %q want %q given, %q", err.Error(), want, "test")
+        }
+    })
+}
+
+func TestAdd(t *testing.T) {
+    t.Run("new word", func(t *testing.T) {
+        dictionary := Dictionary{}
+        dictionary.Add("test", "this is just a test")
+
+        want := "this is just a test"
+        got, err := dictionary.Search("test")
+        if err != nil {
+            t.Fatal("should find added word:", err)
+        }
+
+        if got != want {
+            t.Errorf("got %q want %q given, %q", got, want, "test")
+        }
+    })
+
+    t.Run("existing word", func(t *testing.T) {
+        key := "test"
+        definition := "this is just a test"
+        dictionary := Dictionary{key: definition}
+        err := dictionary.Add(key, "new test")
+
+        if err != ErrWordExists {
+            t.Errorf("got %q want %q", err, "")
+        }
+
+        got, _ := dictionary.Search(key)
+        if got != definition {
+            t.Errorf("got %q want %q given, %q", got, definition, key)
+        }
+    })
+}