Introduction
In English grammar, the base form of a verb functions as the plural form in the present tense (e.g., used with pronouns like 'they'). To convert a base verb into the third-person singular form (used with 'he', 'she', or 'it'), standard inflectional rules require appending the suffix '-s' or '-es' based on the verb's final letters.
Rules for Forming Third-Person Singular Verbs
In standard English grammar, regular and irregular verbs modify their endings to agree in number and person with singular subjects in the simple present tense.
1. Verbs Ending in Double '-oo'
When a verb terminates in a double vowel such as '-oo', standard morphological rules dictate adding simply an -s rather than '-es'.
- Woo: Woos
- Boo: Boos
- Moo: Moos
- Coo: Coos
2. Verbs Ending in a Single '-o' Preceded by a Consonant
Verbs that end in a single 'o' preceded by a consonant generally take an -es suffix in formal standard English, although some loanwords or modern variations permit '-s'.
- Forgo: Forgoes (following the standard pattern seen in verbs like go → goes and do → does)
- Lasso: Lassoes (both lassoes and lassos are recognized in contemporary usage, but lassoes remains the traditional standard)
Conclusion
Adhering to standard inflectional rules ensures grammatical accuracy and linguistic precision. Observing the preceding letter and phonological pattern determines whether an '-s' or '-es' suffix is required when forming third-person singular verbs.