Stultorum infinitus est numerus - The number of fools is infinite (Vulgate - Ecclesiastes, Ciracide 1:15 )
Stultum est timere quod vitare non potes - It is foolish to fear what you cannot avoid
Sua tela tonanti - Missiles to the one who is Thundering (Motto of the Royal Ordnance Corp)
suavi loquens - Soft spoken (Diplomatic term)
Suavi mare magno - The pleasing great sea
Suaviter in modo, fortiter in re - Soft in the forms, hard on the bottom
Sub alis sto - We stand under our wings (Thank you: Kevin )
Sub condicionea - Under the condition
Sub cujus pede fons vivus emanat - Under whose base, flows a live source
Sub hasta - Under the lance (That's where the share on the war spoils)
Sub iudice - Under judgement (Legal term - Involved in a judicial process and waiting for a sentence)
Sub lege libertas - Freedom under the law (Motto of Portugal)
Sub limen - Below the threshold (University Term - the subliminal is what hides below the threshold of consciousness)
Sub rosae amo te - I love you under the roses (I love you in silence)
Sub secreto - Under secret
Sub silento - Under silence ( Without notice being taken - Thank you: Leon )
Sub umbra alarum tuarum protege me - Under the shadow of your wings, protect me (Vulgate - Psalm 16:7)
Sub umbra floreo - Under the shade I flourish (Motto of Belize)
Sublata causa, tollitur effectus - Removing the cause, removes the effect (Medical term)
Substantia individuatur per seipsam - Primordial substance, individualized by being what it is (Definition of "individual", according to the general doctrine of St. Thomas Aquinas)
Succede in arduum - Climb to the hard part (Livy)
Sui Generis - Of its species
Sui iuris - Own rights (Legal Term - Emancipated - Compare with Alieni iuris)
Sum lupi rapantes - I am a raving wolf
Summa Cum Laude - With Greatest Praise (Academic term - Used on degree certificates to indicate exceptional academic standing)
