How to Guess Spanish Words from English: 6 Cognate Ending Rules (-tion, -ty, -ment)

The short answer

If you already speak English, Spanish shares thousands of cognates: words with the same Latin roots and similar spellings. Six ending patterns cover a huge slice of academic, medical, and everyday vocabulary. Swap the English ending for the Spanish one, adjust pronunciation, and you often have the right word. These rules apply when English is your source language.

Why these rules work (and who they are for)

English and Spanish both inherited large amounts of vocabulary from Latin (and, in English, from French). That shared history shows up as predictable spelling pairs. An English speaker can often turn preparation into preparación without looking it up.

These patterns are a vocabulary shortcut for English speakers learning Spanish. The six rules below are worth memorizing if English is already in your head.

Rule 1: -tion becomes -ción

This is the single biggest vocabulary booster. If an English word ends in -tion, change it to -ción in Spanish.

Bonus tip: Almost all of these nouns are feminine, so you use la.

English	Spanish	Notes
nation	la nación	Same root, feminine noun
preparation	la preparación	Stress on the last syllable in Spanish
condition	la condición	Common in medical and legal contexts
celebration	la celebración	Works for most -tion nouns

Rule 2: -ty becomes -dad

If an English word ends in -ty (usually describing a quality or state), swap it for -dad. These are also feminine (la).

English	Spanish	Notes
city	la ciudad	Spelling shifts slightly; still a clear cognate
authority	la autoridad	-ty → -dad pattern
reality	la realidad	Abstract nouns fit this rule often
activity	la actividad	Feminine noun with la

Rule 3: -ce becomes -cia

Words ending in -ce often need an extra a at the end in Spanish: -cia. These nouns are usually feminine.

English	Spanish	Notes
distance	la distancia	-ce → -cia
difference	la diferencia	Very productive pattern
influence	la influencia	Same ending swap
police	la policía	Spelling and stress differ; meaning matches

Rule 4: -ment becomes -mento

For nouns ending in -ment, add an o: -mento. These are masculine, so you use el.

English	Spanish	Notes
instrument	el instrumento	Masculine noun
monument	el monumento	Near-identical spelling
document	el documento	Common in office vocabulary
element	el elemento	Works for many -ment nouns

Rule 5: -al stays -al

This one is a freebie. Hundreds of adjectives (and some nouns) that end in -al are the same in both languages. The main change is pronunciation: in Spanish, stress usually falls on the final syllable (lo-CAL, na-CIO-nal).

English	Spanish	Notes
hospital	el hospital	Same spelling; masculine in Spanish
animal	el animal	Noun stays identical
legal	legal	Adjective, no ending change
local	local	Stress on the last syllable in Spanish
central	central	Very high hit rate for -al adjectives

Rule 6: -ous becomes -oso

If an English adjective ends in -ous, swap that ending for -oso in Spanish.

English	Spanish	Notes
delicious	delicioso	-ous → -oso
famous	famoso	Gender agreement: famosa, famosos, famosas
nervous	nervioso	Describes a person or state
curious	curioso	Same root, predictable ending

Quick reference: all six rules

Rule	English ending	Spanish ending	Typical gender
1	-tion	-ción	feminine (la)
2	-ty	-dad	feminine (la)
3	-ce	-cia	feminine (la)
4	-ment	-mento	masculine (el)
5	-al	-al	varies (often el + noun, or adjective)
6	-ous	-oso	adjective (agrees with noun)

Watch out: false friends break the pattern

These six rules work roughly 90% of the time for English-to-Spanish cognates. The rest are false friends: words that look related but mean something different. Guessing embarrassed → embarazada is a classic trap (embarazada means pregnant, not embarrassed).

A few high-frequency traps to remember:

English word	Looks like Spanish	What it actually means
embarrassed	embarazada	pregnant (say avergonzado/a for embarrassed)
actual	actual	current, present (not “real”; use real or verdadero)
sensible	sensible	sensitive (not “sensible”; use razonable or sensato)
library	librería	bookstore (biblioteca is library)

For a longer list, common traps, and how to practice them in context, read our guide to Spanish false friends for English speakers.

Practice tip: test the rule, then verify

When you meet a new English word, try the matching ending rule, say the Spanish word aloud, and then confirm in a dictionary or in a sentence. LinGoat helps you practice cognates and false friends in full sentences so you learn both the pattern and the exceptions. See how LinGoat works or start practicing.