8. A computing device comprising: one or more computer processors; an output component; a presence-sensitive input component; and a memory comprising instructions that when executed cause the one or more computer processors to: output, for display at the output component, a graphical user interface that includes a text edit region and a graphical keyboard; receive an indication of a first input detected at a first location of the presence-sensitive input component, wherein the first location of the presence-sensitive input component corresponds to a region of the output component at which the graphical keyboard is displayed; determine, based at least in part on the indication of the first input, a new character string that is not included in a language model of the computing device; add, to the language model, the new character string and a corresponding likelihood value associated with the new character string; receive an indication of a second input detected at a second location of the presence-sensitive input component, wherein the second location of the presence-sensitive input component corresponds to the region of the output component at which the graphical keyboard is displayed; predict, based on the indication of the second input and the likelihood value associated with the new character string, the new character string and an input context associated with the second input; responsive to predicting the new character string, output, for display within the text edit region, the new character string; receive an indication of a third input detected at a third location of the presence-sensitive input component, wherein the third location of the presence-sensitive input component corresponds to the region of the output component at which the graphical keyboard is displayed; and responsive to determining that the third input deletes the new character string from the text edit region after being output for display: remove, from the text input region, the new character string; and decrease, at a rate or magnitude that is adapted to the input context, the likelihood value associated with the new character string without removing the new character string from the language model.
13. The computing device of claim 8 , wherein the memory comprises instructions that when executed by the one or more computer processors cause the one or more computer processors to: after decreasing the likelihood value associated with the new character string, receive an indication of a fourth input detected at a fourth location of the presence-sensitive input component, wherein the fourth location of the presence-sensitive input component corresponds to the region of the output component at which the graphical keyboard is displayed; responsive to predicting, based on the indication of the fourth input and the likelihood value associated with the new character string, the new character string, output, for display within the text edit region, the new character string; receive an indication of a fifth input detected at a fifth location of the presence-sensitive input component, wherein the fifth location of the presence-sensitive input component corresponds to the region of the output component at which the graphical keyboard is displayed; responsive to determining that the fifth input deletes the new character string from the text edit region after being output for display: remove, from the text input region, the new character string; and decrease the likelihood value associated with the new character string without removing the new character string from the language model; and after decreasing the likelihood value associated with the new character string responsive to determining that the fifth input rejects the new character string after being output for display and responsive to determining that the likelihood value is a zero or null value, remove the new character string from the language model.