Antonyms for the phrase "count by one" could include "skip" or "jump". Skipping implies a more sporadic counting method, where numbers are deliberately left out when counting a sequence. Jumping, on the other hand, suggests counting in larger increments than one, such as counting by twos, threes, or tens. Another antonym could be "reverse", which would involve counting backwards from a starting number rather than forwards. Lastly, "estimate" could be seen as an antonym, as it involves making an educated guess or approximation rather than precisely counting by ones.