tyfu - to grow, to increase
In the sample sentence above on this page you will observe that the spelling of one word ( bethau ) differs from the spelling on the relevant Geiriadur listing page ( Peth - Thing ) Be not alarmed!
This happens because:-
"Welsh, as with all other Celtic languages, often sees changes made to the beginning of words depending on the word that precedes it, or the role it plays in the sentence. These changes are known as "mutations", of which Welsh has three distinct types. Common situations in which a mutation may occur are when a word follows a preposition, possessive, or number."
The three types of mutation are:-
The three links above will take you to further information about these commonly occurring mutations.
Most Welsh courses and teachers advise students not to worry too much about this at the outset. Fluent speakers will understand you if you forget to mutate a letter. With practice this will come naturally and there is perhaps, no need for beginning learners to make a conscious effort to apply these rules.
However, if you wish to acquaint yourself with the rules early on you could look out for the 'Mutant Alert' notice on the vocabulary pages and use these as an opportunity to refresh your knowledge by checking the above links.
Spot the Mutation: The mutation above is an example of a ........... mutation?
PRESENT TENSE - AFFIRMATIVE
Dwi'n tyfu - I am growing
Wyt ti'n tyfu - You are growing (familiar)
Mae e'n tyfu / Mae hi'n tyfu - He / She is growing
Dyn ni'n tyfu - We are growing
Dych chi'n tyfu - You (plural) are growing (also singular formal)
Maen nhw'n tyfu - They are growing
PRESENT TENSE - NEGATIVE
Dwi ddim yn tyfu - I am not growing
Dwyt ti ddim yn tyfu - You are not growing (familiar)
Dydy e ddim yn tyfu / Dydy hi ddim yn tyfu - He / She is not growing
Dyn ni ddim yn tyfu - We are not growing
Dych chi ddim yn tyfu - You (plural) are not growing (also singular formal)
Dyn nhw ddim yn tyfu - They are not growing
PRESENT TENSE - INTERROGATIVE
Ydw i'n tyfu? - Am I growing?
Wyt ti'n tyfu? - Are you growing? (familiar)
Ydy e'n tyfu / Ydy hi'n tyfu? - Is he / Is she growing?
Ydyn ni'n tyfu? - Are we growing?
Ydych chi'n tyfu? - Are you (plural) growing? (also singular formal)
Ydyn nhw'n tyfu? - Are they growing?
QUESTION - ’NO / YES’ REPLIES
Ydw i'n tyfu? - (Nac) Wyt / (Ydych - formal)
Wyt ti'n tyfu? - (Nac) Ydw
Ydy e'n tyfu / Ydy hi'n tyfu? - (Nac) Ydy
Ydyn ni'n tyfu? - (Nac) Ydyn / Ydych
Ydych chi'n tyfu? - (Nac) Ydyn / (Ydw - formal)
Ydyn nhw'n tyfu? - (Nac) Ydyn
N.B. 'Wyt ti' is the familiar form of the 2nd person and should be used only when addressing close friends, family members and animals. 'Dych chi' is the polite form and should be used in all other instances.