Cuimhne [KWIV-neh]:

Tá cuimhne agam air sin.  I remember that. 

Tá cuimhne na seacht nduine [NIN-yeh] aici.  She has a wonderful memory, lit. the memory of (the) seven people.

cuimhní cinn, reminiscences, memoirs

cuimhneamh [KWIV-nyav or KWIV-nyoo or KWIV-neh]

cuimhneamh míosa [KWIV-nyav MEE-uss-uh], month’s mind

cuimhneamh ar bheart [er^zh v^yart, v^y like the “v” in “view”] (to think of a plan):

Go minic cuimhníonn Hermione ar bheart nuair a bhíonn Harry agus Ron fós ag caint, (Often Hermione thinks of a plan while Harry and Ron are still talking). 

And finally, what’s the opposite of all this?  Well, we could start with the ordinary degree of forgetfulness that affects most of us.

Some ways to say “to forget” are:

dearmad a dhéanamh [YAYN-uv] ar X (very lit. “to make a forgetting on X).  Ex. Rinne mé dearmad air sin (I forgot that, lit.  I made a forgetting on that).  This is the most common phrase for this purpose, in my experience.

X a ligean i ndearmad [ih N^yAR-mud] (lit. to let X into forgetting).  Ex.  Lig sé sin i ndearmad (He forgot that, lit. he let that into forgetting).

“Dearmad” can also mean “mistake” or “omission, as in “Rinne sé dearmad sa rud sin” (He made a mistake in that). 

A few more frásaí dodhearmadta [FRAWSS-ee duh-YAR-muh-tuh] (unforgettable phrases):

Mo dhearmad! [muh YAR-mud, silent “d”] (I forgot, lit. “my forgetting”); a widely used phrase.

seanfhocal (a proverb): Dearmad bhean an tí ag an gcat [DJAR-mud van uh tchee egg uh gaht].  Whatever the housewife forgets is “at” (beneficial to) the cat (presumably food scraps, etc.). For pronunciation, note the “bh” as “v”, the omission of the “n” of “an” in typical pronunciation (all dialects) and the eclipsing of the “c” of “gcat.” 

Cuir ceirín den dearmad leis! (Forget about it!, very lit. put a poultice of forgetting with it!).  Not particularly common, fad m’eolais, but intriguing, especially if you can imagine Johnny Depp talking to Al Pacino about poultices, i nGaeilge, ar ndóigh. 

And getting a little more full-fledged about it, there are two words for “amnesia”

ainmnéise, basically an adaptation from the medical term, itself derived from Greek.  Bhí aimnéise ar Gregory Peck sa scannán Hitchcock “Spellbound.”  Cé a leigheas é?  Ingrid Bergman, mar an Dr. Constance Petersen.

díth cuimhne, which means “loss of memory.”  This phrase uses the word “díth” (loss, lack, need, or want), which is found especially in Northern Irish, as in the question “Cad é atá de dhíth ort?” (What do you want/need/lack?, lit. What is of lack on you?).

This last phrase is a lot like the traditional English street-cry “What d’ye lack?”  Although I don’t think anyone really says it today (certainly not my local Wal-Mart greeter!), you might remember it from some earlier authors, like Oscar Wilde’s “The Fisherman and his Soul” or Richard Dering’s “The Cries of London.”  Or, well, a play by Thomas Dekker that I’ll leave unnamed for this “blag a thacaíonn le teaghlaigh.” 

When translating the phrase “de dhíth” into English, one usually chooses “lack,” “need,” or “want,” depending on context.  One could pick more specific words, ach sin ábhar blag éigin eile!   

Gluais: a thacaíonn le teaghlaigh [uh HAHK-ee-un le TCHAL-ee], family-friendly; cad é [KUDJ-AY] = cad = céard; fad m’eolais [fahd MOH-lish], as far as I know