```--- a/src/compiler/float-tran.lisp
+++ b/src/compiler/float-tran.lisp
@@ -636,7 +636,7 @@
(progn

;;; Handle monotonic functions of a single variable whose domain is
-;;; possibly part of the real line. ARG is the variable, FCN is the
+;;; possibly part of the real line. ARG is the variable, FUN is the
;;; function, and DOMAIN is a specifier that gives the (real) domain
;;; of the function. If ARG is a subset of the DOMAIN, we compute the
;;; bounds directly. Otherwise, we compute the bounds for the
@@ -647,8 +647,8 @@
;;; DOMAIN-LOW and DOMAIN-HIGH.
;;;
;;; DEFAULT-LOW and DEFAULT-HIGH are the lower and upper bounds if we
-;;; can't compute the bounds using FCN.
-(defun elfun-derive-type-simple (arg fcn domain-low domain-high
+;;; can't compute the bounds using FUN.
+(defun elfun-derive-type-simple (arg fun domain-low domain-high
default-low default-high
&optional (increasingp t))
(declare (type (or null real) domain-low domain-high))
@@ -672,9 +672,9 @@
;; Process the intersection.
(let* ((low (interval-low intersection))
(high (interval-high intersection))
-                        (res-lo (or (bound-func fcn (if increasingp low high))
+                        (res-lo (or (bound-func fun (if increasingp low high))
default-low))
-                        (res-hi (or (bound-func fcn (if increasingp high low))
+                        (res-hi (or (bound-func fun (if increasingp high low))
default-high))
(format (case (numeric-type-class arg)
((integer rational) 'single-float)
@@ -1253,7 +1253,7 @@
;;; inputs are union types.
#-sb-xc-host ; (See CROSS-FLOAT-INFINITY-KLUDGE.)
(progn
-(defun trig-derive-type-aux (arg domain fcn
+(defun trig-derive-type-aux (arg domain fun
&optional def-lo def-hi (increasingp t))
(etypecase arg
(numeric-type
@@ -1274,8 +1274,8 @@
;; exactly the same way as the functions themselves do
;; it.
(if (csubtypep arg domain)
-                  (let ((res-lo (bound-func fcn (numeric-type-low arg)))
-                        (res-hi (bound-func fcn (numeric-type-high arg))))
+                  (let ((res-lo (bound-func fun (numeric-type-low arg)))
+                        (res-hi (bound-func fun (numeric-type-high arg))))
(unless increasingp
(rotatef res-lo res-hi))
(make-numeric-type
```