23-letter words containing s, e, l, f, i
- tortoiseshell butterfly — any of several nymphalid butterflies of the genus Nymphalis, and related genera, having orange-brown wings with black markings
- transcendental function — a function that is not an algebraic function.
- twin-lens reflex camera — a camera in which the image appears on a ground-glass viewer (focusing screen) after being reflected by a mirror or after passing through a prism or semitransparent glass; in one type (single-lens reflex camera) light passes through the same lens to both the ground glass and the film, while in another type (twin-lens reflex camera) light passes through one lens (viewing lens) to the ground glass and through a second lens (taking lens) to the film, the lenses being mechanically coupled for focusing.
- ulster defence regiment — a former reserve regiment of the British Army based in Northern Ireland
- united states of brazil — former official name of Brazil.
- until hell freezes over — If you say that you will do something until hell freezes over, you are emphasizing that you will do it for a very long time or for ever.
- urea-formaldehyde resin — any of a group of resins formed by the interaction of urea and formaldehyde under conditions that include heat and pH control: used chiefly in the manufacture of buttons, baking enamels, and for making fabrics wrinkle-resistant.
- user interface language — (language, graphics) (UIL) A language for specifying widget hierarchies etc. in OSF/Motif and DECwindows.
- variable life insurance — an insurance policy whose annuity payments or payment to the beneficiary are not fixed but depend on the income earned by the investment of the premiums.