diff --git a/Eask b/Eask
index e9e03f4..15fd27b 100644
--- a/Eask
+++ b/Eask
@@ -17,3 +17,4 @@
 (depends-on "org" "9")
 (depends-on "counsel" "0.13")
 (depends-on "dash" "2.19")
+(depends-on "s" "1.13")
diff --git a/conlanging-eittlandic.el b/conlanging-eittlandic.el
index 6d0cdd1..714561c 100644
--- a/conlanging-eittlandic.el
+++ b/conlanging-eittlandic.el
@@ -29,11 +29,33 @@
 ;;; Code:
 
 (require 'dash)
+(require 's)
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;;                                  Constants                                 ;
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
+(defconst conlanging-eittlandic--vowels
+  '("a" "e" "i" "o" "u" "y" "á" "é" "í" "ó" "ú" "ý")
+  "Vowels in Eittlandic.")
+
+(defconst conlanging-eittlandic--rounded-vowels
+  '("o" "u" "y" "ó" "ú" "ý")
+  "Rounded vowels in Eittlandic.")
+
+                                        ; Adjectives ;;;;;;;;;;;;;;;;;;;;;;;;;;
+(defconst conlanging-eittlandic--adjective-inflexion-common
+  '("r"  "" "um" "s" "ar" "" "um" "ar")
+  "Declensions of Eittlandic adjectives for the common gender.
+
+See also `conlanging-eittlandic--strong-common-noun-declension'.")
+
+(defconst conlanging-eittlandic--adjective-inflexion-neuter
+  '("t" "t" "um" "s" ""  ""  "um" "r")
+  "Declensions of Eittlandic adjectives for the neuter gender.
+
+See also `conlanging-eittlandic--strong-common-noun-declension'.")
+
                                         ; Verbs ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
 (defconst conlanging-eittlandic--generic-verb-inflexion-indicative-present
@@ -133,6 +155,10 @@ See `conlanging-eittlandic--strong-common-noun-declension' for more info.")
 
                                         ; Generic ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
+(defun conlanging-eittlandic--string-ends-with-p (str suffix)
+  "Determine whether STR ends with SUFFIX."
+  (string-match (regexp-quote suffix) str (- (length str) (length suffix))))
+
 (defun conlanging-eittlandic--maybe-underlying-vowel (underlying-vowel default-vowel)
   "Return which underlying vowel should be used.
 
@@ -152,7 +178,7 @@ UNDERLYING-VOWEL is non-nil."
 
 (defun conlanging-eittlandic--generate-declension-from-table (root underlying-vowel table)
   "Decline a ROOT (with maybe an UNDERLYING-VOWEL) with TABLE."
-  (seq-reverse
+  (reverse
    (let (result)
      (dolist (declension table result)
        (push (concat root
@@ -160,13 +186,92 @@ UNDERLYING-VOWEL is non-nil."
                      (cdr declension))
              result)))))
 
+                                        ; Adjectives ;;;;;;;;;;;;;;;;;;;;;;;;;;
+(defun conlanging-eittlandic--starts-with-any-p (str list)
+  "Check whether STR start with any element of LIST."
+  (seq-some (lambda (elt) (s-starts-with-p elt str)) list))
+
+(defun conlanging-eittlandic--ends-with-any-p (str list)
+  "Check whether STR end with any element of LIST."
+  (seq-some (lambda (elt) (s-ends-with-p elt str)) list))
+
+(defun conlanging-eittlandic--ends-with-a-vowel-p (str)
+  "Return whether STR end with a vowel."
+  (conlanging-eittlandic--ends-with-any-p str conlanging-eittlandic--vowels))
+
+(defun conlanging-eittlandic--starts-with-a-vowel-p (str)
+  "Return whether STR start with a vowel."
+  (conlanging-eittlandic--starts-with-any-p str conlanging-eittlandic--vowels))
+
+(defun conlanging-eittlandic--ends-with-a-vowel-p (str)
+  "Return whether STR start with a vowel."
+  (conlanging-eittlandic--ends-with-any-p str conlanging-eittlandic--vowels))
+
+(defun conlanging-eittlandic--ends-with-a-rounded-vowel-p (str)
+  "Return whether STR start with a rounded vowel."
+  (conlanging-eittlandic--ends-with-any-p str conlanging-eittlandic--rounded-vowels))
+
+(defun conlanging-eittlandic--generate-adjective-declension-from-table (root table)
+  "Generate an adjective's declensions from its ROOT.
+
+The TABLE stores the adjective’s declensions.
+
+If the declension starts with a vowel, then a \"v\" will be
+inserted before it if the root ends with a rounded vowel.
+Otherwise, if any other vowel ends the root and the declension
+starts with a vowel, the last onsonant of the declension will be
+inserted before the declension itself.
+
+We assume here any former long vowel cannot be unstressed."
+  (reverse
+   (let* (declensions
+          (root-ends-with-vowel (conlanging-eittlandic--ends-with-a-vowel-p root))
+          (root-ends-with-rounded-vowel (conlanging-eittlandic--ends-with-a-rounded-vowel-p root)))
+     (dolist (declension table declensions)
+       (push
+        (let ((declension-starts-with-vowel (conlanging-eittlandic--starts-with-a-vowel-p declension)))
+          (cond
+           ((and root-ends-with-rounded-vowel declension-starts-with-vowel)
+            (concat root "v" declension))
+           ((and root-ends-with-vowel declension-starts-with-vowel)
+            (concat root (s-right 1 declension) declension))
+           (t (concat root declension))))
+        declensions)))))
+
+(defun conlanging-eittlandic--make-adjective-declension (root gender)
+  "Create declensions for an Eittlandic adjective.
+
+The declension is based on the adjective’s ROOT and the GENDER it
+agrees with."
+  (conlanging-eittlandic--generate-adjective-declension-from-table
+   root
+   (if (eq 'common gender)
+       conlanging-eittlandic--adjective-inflexion-common
+     conlanging-eittlandic--adjective-inflexion-neuter)))
+
+(defmacro conlanging-eittlandic--build-adjective-declension-org ()
+  "Just to avoid typing all of this out."
+  `(format "| | Common | Neuter |
+|---------+--------+--------|
+| Sg.Nom. | %s | %s |
+| Acc.| %s | %s |
+| Dat.| %s | %s |
+| Gen.| %s | %s |
+| Pl.Nom. | %s | %s |
+| Acc.| %s | %s |
+| Dat.| %s | %s |
+| Gen.| %s | %s |"
+           ,@(reverse (let ((i 0)
+                            declensions)
+                        (while (< i 8)
+                          (dolist (gender '(common neuter) declensions)
+                            (push `(nth ,i ,gender) declensions))
+                          (setq i (1+ i)))
+                        declensions))))
+
                                         ; Verbs ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 (defmacro conlanging-eittlandic--build-verb-declension-org ()
-  "Just to avoid typing all of this out.
-
-ROOT, IMPERATIVE-PASSIVE, PRESENT-PARTICIPLE, PAST-PARTICIPLE,
-IND-PRES, SUBJ-PRES, PAST, and PASSIVE are all different forms of
-the verb that will be inserted in the org text."
+  "Just to avoid typing all of this out."
   `(format "Declensions:
 - infinitive :: %s
 - imperative :: %s
@@ -278,6 +383,14 @@ list, going in the following order:
 ;;                              Public functions                              ;
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
+;;;###autoload
+(defun conlanging-eittlandic-insert-adjective-declension (root)
+  "Insert adjective declensions of ROOT."
+  (interactive "sAdjective root: ")
+  (let ((common (conlanging-eittlandic--make-adjective-declension root 'common))
+        (neuter (conlanging-eittlandic--make-adjective-declension root 'neuter)))
+    (insert (conlanging-eittlandic--build-adjective-declension-org))))
+
 ;;;###autoload
 (defun conlanging-eittlandic-insert-verb-declension (root strength underlying-vowel)
   "Insert declensions of ROOT in org format at point.
diff --git a/conlanging.el b/conlanging.el
index 557b87c..a3fc06e 100644
--- a/conlanging.el
+++ b/conlanging.el
@@ -3,7 +3,7 @@
 ;; Author: Lucien Cartier-Tilet
 ;; Maintainer: Lucien Cartier-Tilet
 ;; Version: 0.1.0
-;; Package-Requires: ((emacs "29") (org "9") (ivy "0.13") (counsel "0.13") (dash "2.19"))
+;; Package-Requires: ((emacs "29") (org "9") (ivy "0.13") (counsel "0.13") (dash "2.19") (s "1.13"))
 ;; Homepage: https://labs.phundrak.com/phundrak/conlanging.el
 ;; Keywords: convenience